New plugin 'tdcmq'

Dispatches messages from dispatch/irc MQ topic to IRC

Message must have keys 'target' and 'msg'
Add message queue for privmesg

TODO:
- should it be for all messages? i.e. for bot/core.rb #send_cmd?
- should I try to empty it in many takes, instead of one take? i.e.
return to loop early, and empty queue again in next iteration?