Tab-completion changes:
- in empty line, it completed /MSG nick1 fine, but another tab press
didn't give the next nick.
- "/command <tab>" doesn't try to complete /command, but instead it tries
to complete it's subcommand or first parameter.
- /MSG completion now goes through nicks in ALL servers prefixing the nick
with -<server tag> if needed.
- /MSG -tag <tab> completes only nicks in "tag" server.
git-svn-id: http://svn.irssi.org/repos/irssi/trunk@388 dbcabf3a-b0e7-0310-adc4-f8d773084564