Changes in version 1.9:

zcmp anf zdiff now meet the POSIX requirement for cmp and diff that the
standard input shall be used only if the file1 or file2 operand refers to
standard input.

zdiff now passes the options '-W' and '-y' to diff. (But it only works if
the diff program used supports them).

Bzip2 and lzip files are now detected better.
('echo LZIP | zcat' and 'echo BZh5 | zcat' no longer return an error).

ztest now continues checking the rest of the files if any input file is a
terminal.

'ztest -v' now prints the number of files that failed the test (like lzip).

zcat, zgrep, and ztest now check for errors when closing the input file in
addition to checking when closing the input from the decompressor.

Trailing data remaining in the data feeder to the decompressor are now
correctly ignored.

zupdate has been modified to support the new behavior of lzip 1.22's option
'-o' while retaining:
perfect backwards compatibility with older versions of lzip down to 1.20,
good backwards compatibility with older versions of lzip down to 1.11,
acceptable backwards compatibility with older versions of lzip down to 1.4.

zupdate now keeps combined extensions: tgz, tbz, tbz2, txz --> tlz.
This is useful when recompressing Slackware packages, for example.

zupdate now puts single quotes around file names when calling zcmp to allow
file names with spaces. (But putting spaces in file names is a bad idea).

The descriptions of zcat, zcmp, and zdiff have been improved.
