Prevent liners from turning while not running

Fix bugs wthen turning during level transitions.

Prevent players from turning before round start, even if they have
reached their own spawn point already.

Player.gd

@@ -90,6 +90,9 @@ func generate_wall():
 	grid.set_cell(posix - dirx, posiy - diry, 1)
 
 func prepare_turn(left_or_right:int):
+	if !running:
+		return
+
 	var current_angle = (dire + dire_delta) * 90
 
 	dire_delta += left_or_right