Implement dealer connection status

[igor-sirotin]

We don't have any information if we stopped receiving state from the dealer.

Possible ways:

• make a timeout for State (then dealer should send it periodically)
• process playerOnline state by all players. Then dealer's playerOnline state will also work (now it just doesn't).

Probably something similar to ● Waku: N peer(s) next to the Room.
Or maybe just show when the last state was received.