IRCd:Modularized commands

This proposal would complete the modularized protocol handlers and tuple-queue triad. In this system, a protocol handler module parses an incoming protocol message, generating a tuple from it. This tuple is then passed to the actual command implementation, which would presumably be looked up in a list of commands installed by modules. The command implementation has to apply access controls, which is somewhat unlike the existing ircd-darenet, but the change means that multiple protocols may be supported simply by writing a protocol parser that produces a tuple to pass to the command processor.