New manpage compression support. Only one macro controls compression

New manpage compression support.  Only one macro controls compression
now, DO_COMPRESS.  This controls whether or not catpages are compressed or
not (on by default, since little else uses the catpages and those few things
that do can always configure in a `zmore' in place of more or something, and
saving space is more important, IMHO).

Uncompression support is now on by default since that's the only way to support
mixed-mode environments.  If you don't like it, just don't compress your man
pages and it won't be used! :-).  Supports gzip.  You can also compress
the man pages themselves (or gzip them) now and it will work.