Instead of passing around pointers to the Server, Server::Get() returns
the server's pointer (simplifying some things a good bit).
As a result, headers have been cleaned up, and some redundant KeyMaps
have been placed in Maps.h.
A new class was added (ChatCommand) to represent commands, which are
all stored in the Server iself.
A command can be assigned any arbitrary BMessage, and can be given
arguments with some semantic meaning (so far just "string" or "room
participant," etc).
"invite" and moderation commands were added (ban/kick/mute etc).