Make IrcParser functional

IrcParser now parses incoming raw data from the ircd and generates the appropriate
IrcEvents from the input. Most of this can be automated via QMeta* stuff, though several
irc commands need special casing for decoding the input (default is just to use serverDecode(),
as this is almost always the right thing to do).

All IrcEvents thus have their parameters as properly decoded QStrings, so we don't need to care
about this anywhere else.

NOTICE and PRIVMSG get some more special handling; multiple targets are broken up into
sending one event for each, messages are decrypted if appropriate, and channel welcome messages
are properly redirected.