Added dynamic tic stabilization

Attempts to balance periods of rough traffic by putting in an artificial delay, smoothing playback but further increasing input delay. This can be disabled with net_ticbalance.

src/common/engine/i_net.h

@@ -11,6 +11,7 @@ enum ENetConstants
 	BACKUPTICS = 35 * 5,	// Remember up to 5 seconds of data.
 	MAXTICDUP = 3,
 	MAXSENDTICS = 35 * 1,	// Only send up to 1 second of data at a time.
+	STABILITYTICS = 12,
 	LOCALCMDTICS = (BACKUPTICS * MAXTICDUP),
 	MAX_MSGLEN = 14000,
 };