Beginning work on multi server support

Some files have been moved, others have been deleted.
There is now a new Server class that handles all the data associated
with
the connection to an IRC server. Plugins will now have to deal with
making
a connection to an IRC server. Most events will also have a Server
object
associated with them.
How data and the connection to IRC is handled will be rewritten as well.
For the moment, there are only method signatures without bodies.
Changed the name of a property in Channel and User
Added server parameter to some methods
Rewrote server data handling
Added server connection, mostly
Finished Server, mostly
Added server handling to IRCQueue
Plugins now loaded from the current directory
Readded IRC parsing
Server now expected to always stay connected
Small changes in server management
Miscellaneous small changes/fixes
Reordered files, changed plugin interface

I'm bad at committing.
Changed plugin interface again, after some persuasion
Better error reporting on loading assemblies
Fix stack overflow when requesting a user
Plugin name not printed twice
Fix exception thrown when handling exception
Fix wrong data being lost on channel/user drop