Kindo begun to use a ChangeLog file. That gives (IMHO) better detail about the changes done to the sources.

since 0.13.2
- reLyX 2.9.2.1: -n option allows noweb files (Sylvan)
- reLyX 2.9.1.1: Windows compatible! Minor bug fixes/command additions (Karger)
- reLyX 2.9: graphics commands. Also several bug fixes (Karger)
- reLyX 2.8.1.2: directory bug fix (Karger)
- reLyX 2.8.1.1: -o option, bug fixes, a couple new commands (Karger)
- reLyX 2.8: (Karger)
  -- verbatim & \verb
  -- -h option
  -- translate math commands (e.g., \sp -> ^). Configurable.
  -- translate certain arguments to untranslatable commands as regular
     LaTeX (e.g., second argument to \rotatebox). Configurable.
  -- translate a few more simple commands + various small bug fixes
  -- kernel cleanup
- reLyX 2.7.1.1: support \input and \include. -p option. Whitespace and
  word-wrap more like LyX. Translate commands generated by specific LyX layouts
  (e.g., \lyxaddress). (Karger)
- The icons are now read at run time, so that everybody can add its
  own favourite icon set! (JMarc)
- Added support for localized bind-files and localized documentation 
  (Joacim & JMarc)
- Fixed crash when \kbmap is true, but no keyboard map has been defined (JMarc)
- reLyX 2.6.1.3: support \hfill and optional argument to \cite,plus
  several bug fixes (Karger)
- Removed some old SGI specific code which seems to hurt more than it helps 
  (JMarc)
- Change the spellchecker to reject collated words like 'wellcome' by
  default. See lyxrc if you do not like that (JMarc)
- Fix the spellchecker so that it ignores text marked as LaTeX (JMarc)
- New dinbrief.layout from Carsten Kaemmerer & Jrgen (JMarc)
- added Latex8.cls support -- IEEE conference papers (no docs yet) (ARRae)
- Add definition of the lyxcode environment for the slides textclass (JMarc)
- Updated lib/layout/ directory from lyx0_12
- reLyX 2.6.1.2: Lots of bug fixes, support for BibTeX commands (Karger)
- Changed the table-layout to a tabbed form (Jug)
- Finish porting paragraph-layout, removed all old code (Jug)
- Ported the paragraph-layout-forms to the frontend-stuff (Jug)
- Added also form_table to the new xforms-table-stuff (Jug)
- Removed all forms from lyx/forms which have been already ported
  to the new frontends/xforms directory (Jug)
- Removed all table-gui code from lyx_cb.C, lyx_gui.C and lyx_gui_misc.C (Jug)
- Fixed the LaTeX-Log (in frontends/xforms) and removed LaTeXLog.C (Jug)
- Ported the Tabel-Layout stuff to frontends/xforms and
  removed TableLayout.C (Jug)
- Updated table.[Ch] to reflect the changes I made in 0.12 (Jug)
- Added protection against !` and ?` ligatures in quote insets (JMarc)
- Added support for the new lyxrc command \relyx_command in
  lib/configure (JMarc)
- Renamed 'Advanced Editing' to 'Extended Features' and removed
  'How do I-' in help menu (John)
- Click on a ToC inset, and the ToC pop-up appears. Haven't tested it. (Asger)
- Improved logic on File Open with already opened documents. (Asger)
- Fixed crashes when switching documents with open math insets. (Asger)
- Fixed a buglet in MenuNew with already open document. (Asger)
- Fixed LString static initialization problem exposed on RedHat 5.1
  causing crash on File Open. (Asger)
- Added "File->Import" menu to allow direct import of LaTeX and ASCII files.
  Requires Perl5.002 and reLyX to work for LaTeX files. (Asger)
- Nuked the --with-two-colors option, along with all _bw icons (JMarc)
- reLyX 2.6: better table support, \bibitem support, and bug fixes (Amir)
- Disallow include files with textclass different from the master
  document textclass (when creating LaTeX file) (JMarc)
- Fix buglet where typing Return at the beginning of a bibliography
  entry would lose the bibkey inset (JMarc)
- Replaced koma-script textclasses with better ones provided by Bernd 
  Rellermeyer (JMarc)
- Fixed custom-export to that makeDVIOutput is called only if type
  .dvi or .ps is requested (Jug)
- Fixed small bug in producing command for fax_program (Jug)
- Accept floats in bounding box for [e]ps pictures (JMarc)
- fix bug in mathed where an empty fraction would cause a core dump (JMarc)
- Added support for 'Other' spacing in Layout->Document (JMarc)
- Hopefully made lib/configure more robust when latex could not be run
  (JMarc)
- Add missing window-close handler for the paper popup (JMarc)
- Newly created note insets are now empty (JMarc)
- Fixed bug with appendix and table of contents (Matthias)
- added support for multiple packages in \DeclareLaTeXClass for classes that
  need some packages. See for example latex8.layout (JMarc)
- Open bibitems with C-o (open-stuff) at the beginning of a paragraph
  (Matthias)
- do not translate newline to \\ in LaTeX mode (JMarc)
- reLyX 2.5.2.3: Read .lyx/syntax.defaults if possible; always use TeX mode,
  never LaTeX layout, for untranslatable text (Karger)
- broke up lyx.fd and sp_form.fd and moved separated forms into
  src/frontends/xforms/forms                                      (ARRae)
- removed form_title from everything and replaced with gui-indep 
  splashscreen instead. (Only XForms implem. at present)          (ARRae)
- update de.po (Peter)
- reLyX 2.5.2.2: syntax files now contain "regular environments", and -s option
  causes reLyX to read multiple (e.g., user-defined) syntax files (Karger)
- reLyX 2.5.1.1: one major and some minor bug fixes (Karger)
- really fix (??) the tendency of lib/configure to nuke useful files (JMarc)
- Fixed bug with newlines in tables (Juergen)
- Added appendix support from Matthias. No menu or doc for now (use the
  `appendix' function to toggle) (JMarc)
- LaTeX generation cleanup 
  -- extracted common code into separate functions to improve maintainability
  -- fixed a font generation bug as a result                      (ARRae)
- Initial gui independence test in src/frontend
  only one popup (LaTeXPreamble) with xforms + qt implementations (ARRae)
- LString::srep empty_rep static initialisation fixes (ARRae)
- Corrupt layout file segfault fix/workaround (ARRae)
- small speedup of LaTeX generation (about 3%) (ARRae)
- included fix for segfault from lyxlex (ARRae)
- The Makefiles are now generated by automake. Please report what is
  broken. I'm sure there will be plenty of problems (JMarc)
- reLyX 2.5: read in LaTeX command syntax plus bug fixes (Karger)
- Added textclass ejour2 for Springer Journals from Martin Vermeer,
  heavily modified by me; added corresponding documentation to
  AdvancedEditing.lyx and LaTeXConfig.lyx  (JMarc)
- Small fixes here and there (JMarc)

since 0.13.1
- Duplicated rom for math macros. (Alejandro)
- Improved math parser error messages function. Better messages, and
  updates lyxlex line number. (Alejandro)
- Fixed bug reading accented undefined names. (Alejandro)
- Fixed two bugs in layout files handling (JMarc) 
- Fixed a typo in the hu.po translation file below (JMarc)
- reLyX 2.4: Table support! (Also accents and
  center/flush[right|left]) (Karger) 
- Added Hungarian translation and binding file, supplied by Kadar
  Andrs <kadara@eik.bme.hu> and Krmer Pter(JMarc)
- Fixed Insert->Index in menus.bind (JMarc)
- Fixed Layout->Document so that the font size and page headings lists
  are refreshed correctly when switching class, as reported by Kalle
  (JMarc) 
- Updated a but Customization.lyx about layout files parameters
  (JMarc)
- Added new landslide.lyx example, provided by Kimmo Koli (JMarc)
- Changed a bit the citation and index insets, so that the popups are
  closed only when *their* inset is deleted (JMarc)
- Fixed a color problem when using a private colormap (JMarc)
- Improved -dbg option: now you can type 'lyx -dbg info,kbd'; the old
  method has also been kept (JMarc)
- Various clean-up in configure, INSTALL, WHATSNEW, README; removed
  any trace of Insetlatex and Insetlatexdel; removed autocorr.[Ch]
  (JMarc)
- Rewrote the various printxx() methods and functions of kbmap.[Ch] to
  use LString. (JMarc)

since 0.13.0
- WARNING! 0.13.1 does not compile but is released because of me going
  away for a couple of weeks. Also if you are able to compile it, there
  will be some wrong behaving code in there, parts of a cleanup not yet
  done...please have a go at it. (Lgb)
- New textclasses for koma-script package created by Bernd K"ummerlen
  <bkuemmer@ix.urz.uni-heidelberg.de> (JMarc)
- New tag \screen_font_popup in lyxrc, which has the meaning of the
  existing \screen_font_menu; the semantic of the later is changed to
  *really* apply to menus (JMarc)
- Fix to lib/configure: works when LaTeX is broken (JMarc)
- Fixes to configure: recover when perl is not found; add a
  replacement for atexit on SunOS (JMarc)
- Fix to src/Makefile.in: changed the order of libraries and added a
  missing $(LIBOBJS) (JMarc)
- minor doc updates to Tutorial, UserGuide, and Introduction (Karger)
- reLyX 2.3.1.1: lots of bug fixes and support for -c option (Karger)
- two new keymaps and new os2 configure (...)

since 0.12.0
- reLyX 2.3: reads layouts from LIBDIR/layouts/ (Karger) + buglet (JAMatos)
- Fixed a bug regarding the insetbib-popup causing a crash if the inset was
  deleted while the popup was active, same for insetcitation and
  insetindex. (Joacim)
- Changes to the documentation, re the numbers of undo-levels (Joacim)
- A few more _()'s (Joacim)
- Fixed the makepatch command and *really* re-added the reLyX.in
  wrapper :-( (JMarc)
- Fixed(?) problem with bibliography item number broken after 127. Now
  the limit is 255 (JMarc)
- Fixed problem with character  in encodings other than latin1
  (JMarc)
- Removed the CommandTitle tag in layout files and added new tag
  InTitle (JMarc)
- Cleaned up ams layouts, so that Abstract works, among others (JMarc)
- added a LAssert.h for use with assertions. (Lgb)
- changes to figinset to clearify a bit how it works (Lgb)
- some changes to LString to make it more like STL string (Lgb)
- rewrote to use sigaction instead of signal (Lgb)
- removed pathstack.[Ch] replaced with path.h (Lgb)
- fixed a bug regarding melt and added an entry in the reference manual for
  melt (Joacim)
- fixed a few cosmetic bugs in the GUI (Joacim)
- Modified the way dvips is called in File->Print. NOTE THAT YOU WILL
  HAVE TO FIDDLE WITH LYXRC TO PASS THE PRINTER NAME TO DVIPS. This is
  the price to pay to have it work on mis-configured systems (JMarc)
- You can now override the LYX_LIBS variable to make a binary
  distribution of LyX with static libforms and libXpm. (JMarc)
- Fixed bug in reLyX installation and textclass.lst generation (JMarc)
- Fixed problem with inline when not using gcc (JMarc)
- Fixed some warnings reported by SGI CC (JMarc)
- Fixed some problems for the \hlines in longtable-header/footers (Jug)
- endess-loop by converting layouts to linuxdoc belonging to references
  killed (Bernhard)
- extra parameter for Buffer::GetNextParameter. Now it's possible to
  change the convertion behaviour of single characters depending on the
  layout. (Bernhard)
- New wrapper reLyX.in (JMarc & Karger)
- Fix a bug in lib/configure, where files are deleted by mistake
  (JMarc)
- Updates to WHATSNEW, INSTALL, UPGRADING and BUGS.lyx (JMarc)
- configure also checks for the C++ compiler xlC (JMarc)
- reLyX 2.2.3.1: -r and -t to handle unknown environments + buglets (Karger)
- reLyX 2.2.1.1: Bug fixes + added abstract environment (Karger)
- added typecasts to unsigned char for arguments to ctype-functions, to
  fix problems regarding locale+ctype on Solaris2.5 (Joacim)
- added a help text for melt (Joacim)
- new wrapper around reLyX generated by autoconf (Amir & JMarc)
- moved reLyX to lib/ and modified Makefiles for installation and
  binary distribution (JMarc)
- Fixed problems with determination of LyX library dir (JMarc)
- Fix buglet with fonts ; fixed buglet with installation of .mo
  files. (JMarc)
- Updated `problems' section of INSTALL (JMarc)
- use g++ for compilation if this is possible (JMarc)
