Ignore .elc files.
Reformat copyright information.
Reformat commentary.
Update installation instructions.
Fix typo.
Update information about caveat.
Remove commented out code and associated comments.
Remove information about irreproducible bug.
Remove code that ensures compatibility with XEmacs.

I don't use XEmacs, so these portions of the code are obsolete to me,
and I have no way of testing them.
Update compatibility information.