[All Protocol] BLOCK command and unblock list

[mixflame]

True antitrolling features are needed to move some of the bigger channels off of IRC

BLOCK command: not a kick, not a ban*

*yes, it's really just BAN command renamed

BLOCK::!!::handle

UNBLOCK::!!::handle

Block and unblock the Handle's IP (add/remove from blocklist)

Not called ban because there are no banhammers in GlobalChat