Breath cheat fix: server side

Breath is now handled server side. Changing this behaviour required some modifications to core:

* Ignore TOSERVER_BREATH package, marking it as obsolete
* Clients doesn't send the breath to server anymore
* Use PlayerSAO pointer instead of peer_id in Server::SendPlayerBreath to prevent a useless lookup (little perf gain)
* drop a useless static_cast in emergePlayer

src/remoteplayer.cpp

@@ -148,7 +148,7 @@ void RemotePlayer::deSerialize(std::istream &is, const std::string &playername,
 		} catch (SettingNotFoundException &e) {}
 
 		try {
-			sao->setBreath(args.getS32("breath"));
+			sao->setBreath(args.getS32("breath"), false);
 		} catch (SettingNotFoundException &e) {}
 	}