Fix OnPlayerSocketConnected never called

Add GameSocket.Send() method

Update README

Fix 'not in game' when trying to spectate game

Fix OnSpectatorConnected called before sending 'cg_info' to the socket

Add SocketCount method to player

Add OnSpectatorConnected callback

Add SpectateFilepath and GettingStartedFilepath config options

Add Leave method to players

Send 'ping' control messages