* Initial "join room" feature.
* React correctly to remotely joined rooms.
* Leaving rooms implemented both locally using the room menu
in nheko, and reacting properly when leaving a room remotely
from another client.
* Validate both inferred and explicitly entered server addresses by attempting to call the /versions endpoint
* If the domain from the mxid fails validation, try prefixing it with 'matrix'
* Only show server address field if address validation ultimately fails
Each HistoryView maintains a list of pending events. Each pending
message is validated from the homeserver with either the returned
EventId or the body of the message.
Currently there is no support to remove invalid messages.
Also some small refactoring:
- ChatPage doesn't know about the message being sent. The message
delivery is solely handled by HistoryViewManager.
- Nick coloring function moved to HistoryViewManager.
