Demos big update

-Added some more math functions
-fixed many memory leaks
-added AABB and BVHTree support to collision.d
 *BVHTree has only incrementally adding entities implemented by now (and bad BottomUp algorithm)
 *ECS Systems use two trees, one for static and one for dynamic entities, dynamic BVH is builded every frame from scratch by now
-BrickBreaker now uses BVHTree to collision detection
 *balls only use tree for checks (they aren't adding to tree)
-fixed bug leading to crash

demos/source/gui/manager.d

@@ -33,6 +33,11 @@ struct GUIManager
     int selected_template = 0;
     int selected_component = 0;
 
+    ~this()
+    {
+        clear();
+    }
+
     void selectTemplate(int id)
     {
         if(templates.length == 0)return;
@@ -133,6 +138,7 @@ struct GUIManager
             edit_components.length = comp.component_id+1;//.extend(comp.component_id + 1);
         }
         //edit_components[comp.component_id] = ComponentEditGUI(name);
+        if(edit_components[comp.component_id].variables)return;
         ComponentEditGUI comp_edit;
         comp_edit.name = T.stringof;
         //enum fields = __traits(allMembers, T);