Create concept of "meta channels" and utilise them for #multiplayer and #spectator

[cg0]

Meta channels should be fake channels that go through it's own custom logic. I have a few ideas:

• Some meta channels can just be hidden channels that can be added to users
• Others can be like the above but utilise an existing user map, e.g. spectating users
• While more advanced meta channels can handle it's own chat events and propagation