-Support for changing fonts

-Detect when free() might crash the project and throw error
-fixed 2D Bounce in physics (3d still broken)
-renamed “on_top” property to “behind_parent”, which makes more sense, old on_top remains there for compatibility but is invisible.
-large amount of fixes

core/message_queue.cpp

@@ -378,11 +378,12 @@ void MessageQueue::flush() {
 			}
 
 		}
-		message->~Message();
 
 		read_pos+=sizeof(Message);
 		if (message->type!=TYPE_NOTIFICATION)
 			read_pos+=sizeof(Variant)*message->args;
+		message->~Message();
+
 		_THREAD_SAFE_UNLOCK_
 
 	}