* AClientHandler.cs:
  Converted abstract methods to virtual.
  Moved command functions from ACommandHandler.
  Made "help" and "commands" command act as default commands.

* IrcClient.cs:
  Added safety check for null type / user / channel information.

* TwitchHandler.cs:
  Initial implementation of user tracking and stats.

* Program.cs:
  Converted to work with the newer command "system".
  
* ACommandHandler.cs:
  Removed due to a newer "system" that allows client handlers to implement commands directly.