Merging two other Debian fixes in preparation for a 3.2.2-1 upload.
3.2.2-1. Minor change, removed very old compatibility kludge.
Debian bug #764181: Accidentally had an LGPL header in a bunch of files.
Replaced them with GPL headers where possible. OSCAR and Twitter modules
can't be relicenced though, so add an LGPL blurb to debian/copyright.
doc/AUTHORS updated to the current state of things.
cmd_otr_keygen: improve argument parsing
Require libotr 4.0.0 instead of the version it was compiled with

With the OTRL_INIT macro, building against 4.1.0 results in bitlbee
refusing to run if the installed libotr version is 4.0.0, even though
they are compatible and we don't use the new exposed APIs of 4.1.0
README: Remove workflow notes
README: coverity badge, pull requests, external workflow notes