Copyright and version headers update.

Copyright and version headers update.
Remove some outdated comments through the whole file.
(vc-bzr-program-args): Remove because unused.
(vc-bzr-log-switches): New customization option.
(vc-bzr-command): Use LC_MESSAGES=C instead of LC_ALL=C.  No longer
use `vc-bzr-program-args'.
(vc-bzr-register): Fix for working with both 22.1 and CVS version of
`vc-find-root' (patch by Andreas Hoenen).
(vc-bzr-status): Update regex to match latest Bzr output.
Remove redundant test.
(vc-bzr-init-version): New function.
(vc-bzr-unregister): Must not delete file.
(vc-bzr-find-version): New function.
(vc-bzr-checkout): Argument `rev' is explicit revision only if it's
a non-empty string, otherwise take head revision.
(vc-bzr-print-log): Pass `vc-bzr-log-switches' to "bzr log".
(vc-bzr-diff): Simpler build of the revision spec string.
(vc-annotate-convert-time, vc-bzr-annotate-difference):
Remove: compatibility hacks for Emacs21, not needed in Emacs 22.
(vc-bzr-dir-state): Add code comments.  Removed redundant statement.
(vc-bzr-dired-state-info): Only provide custom strings for
overloaded VC state 'edited; otherwise fallback to
`vc-default-dired-state-info'.