Bullshit v4 (source & tooling).

This is a rewrite of the Bullshit bulletin lister. Should have all
the same features as v3, but much faster at lightbar navigation
and especially better at scrolling large files. (frame.js has been
replaced here by my new screen management library, 'swindows'.)

Sysops don't need to concern themselves with the files in this
commit; the build generated from these has been placed in the same
location as the old 'bullshit.js' script. Just copy that one to
wherever you normally run this from and it'll take over. Or you
could run Bullshit from the repo if you like to live dangerously.