Changes to support ChangeLog.10+.

Changes to support ChangeLog.10+.
(main): Tidy up usage string.  Fix "Use of uninitialized value" warning.
Set version to 0.2.  Parse the directory listing to get any ChangeLog.n
file, not just 1..9.
(header_match_p, entry_match_p, print_log, parse_changelog): Remove Perl
prototypes (their purpose is to help the parser, which isn't needed here,
not declare arguments).
(parse_changelog): Make --reverse faster on big batches by not modifying
the entries list.