Extending Base Chat system

[cmcintosh]

• [ ] Create Chat Command system for declaring Slash Commands, handling permissions for use, and executing them.
• [ ] Add ability to link Users / Items in chat.
• [ ] Create UI for displaying links, or interacting with users clicked on from chat.
• [ ] Create, Join, Leave Channels
• [ ] Send Private messages to other users
• [ ] Mute/Block other users
• [ ] Flag abusive messages