bot:  abstract channels

Move channels to their own class.  This greatly simplifies the lines of
code in the protocol per line received as well as allowing per-channel
configuration.  Currently said configuration is just for the used
plugins.
bot:  fix format string
bot:  set lineRate to prevent excess flood

Via testing, 0.5 seems to be the lowest we can get away with.
linker:  remove SyntaxWarning about global