BGE 2D Filters: filters run per scene now (fix for [#18152]) - it (slightly) breaks backward compatibility !!!

Originally we had 2DFilters (m_filtermanager) stored in RenderTools. That way filters were stored globally and were being called once per each scene. This was producing two big problems: (1) performance and (2) flexibility of use.

(1) Performance - To run the filters 2X == 2X slower
(2) flexibility of use - Very often we want the filter in the scene but not in the UI for example.

For those reasons I believe that 2DFilters with multiple scenes was very useless or unpredictable. I hope they work fine now.
To make it work as before (2.4) you can simply recreate the 2dfilter actuators across the scenes.

* * * * *

Imagine that we have:
(a) Main Scene
(b) Overlay Scene

in Main Scene the Z Buffer and RGB will be from the main scene.
in Overlay Scene the Z Buffer will be from the Overlay Scene and the RBG buffer is from both [(a + 2D Filter) + b].

So in pseudo code if we have a,b,c,d,e scenes we have: (2DFilterE(2DFilterD(2DFilterC(2DFilterB(2DFilterA(a) + b) + c) + d) + e)

source/gameengine/BlenderRoutines/KX_BlenderRenderTools.cpp

@@ -379,13 +379,3 @@ void KX_BlenderRenderTools::MotionBlur(RAS_IRasterizer* rasterizer)
 		}
 	}
 }
-
-void KX_BlenderRenderTools::Update2DFilter(vector<STR_String>& propNames, void* gameObj, RAS_2DFilterManager::RAS_2DFILTER_MODE filtermode, int pass, STR_String& text)
-{
-	m_filtermanager.EnableFilter(propNames, gameObj, filtermode, pass, text);
-}
-
-void KX_BlenderRenderTools::Render2DFilters(RAS_ICanvas* canvas)
-{
-	m_filtermanager.RenderFilters(canvas);
-}