The "general options" section of the manpage(s) has become quite
cluttered, and some of the options are obscure things most people don't
need to know about. Move the really obscure ones into their own category
near the end of the manpage, and factor out the options used when
starting a game from the command line into their own section as well.
Also add some missing doc comments for Hexen command line options.
ceefa5bbd9