* Allow access to subsystems by identifier.
* Added Source to Message struct.
* Avoid conflicts.
* Added Join / Part methods.
* Correctly handle replying to users directly.
* Fixed SendCommand's identifier.
* Correctly set Source when redirecting messages.
* ExecCommands requires auth now.
* Split up Join & Part commands.
* Added auth subsystem.
* Added AuthCommand.
* Added PartCommand.
* Use new commands.