Fix the lobby slots.

- lobbyInfo.Slots is now a dictionary, keyed by the name of the PlayerReference that the slot is tied to.
 - LockRace/Color/Team is now specified on the slot, avoiding map lookups in the lobby
 - Observers are no longer tied to slots -> players will join as observers instead of crashing the game if there are no available slots
 - Observers are able to change their name and color

OpenRA.Mods.RA/ServerTraits/MasterServerPinger.cs

@@ -66,7 +66,7 @@ namespace OpenRA.Mods.RA.Server
 								server.lobbyInfo.Clients.Count,
 								string.Join(",", Game.CurrentMods.Select(f => "{0}@{1}".F(f.Key, f.Value.Version)).ToArray()),
 								server.lobbyInfo.GlobalSettings.Map,
-								server.lobbyInfo.Slots.Count( s => !s.Spectator )));
+						        server.Map.PlayerCount));
 
 							if (isInitialPing)
 							{