Changes in version 0.13:

Skipping of unreadable files during multi-threaded archive creation with
per-file compression has been fixed. Tarlz did produce empty lzip members,
and sometines left the last files out of the archive.

Multi-threaded listing of tar.lz archives containing empty lzip members has
been fixed. It listed members out of order and sometimes hung.

When creating an archive, negative modification times are now stored as cero
(1970-01-01 00:00:00 UTC). Negative times are not portable.
