Remove hard coded paths pass 1

- displaySplashWindow() now takes an optional path to a bitmap file.
- Missing, unavailable and warning texture paths now come from
GFXTextureManager static methods.

Engine/source/materials/processedMaterial.cpp

@@ -30,9 +30,9 @@
 #include "materials/materialManager.h"
 #include "scene/sceneRenderState.h"
 #include "gfx/gfxPrimitiveBuffer.h"
+#include "gfx/gfxTextureManager.h"
 #include "gfx/sim/cubemapData.h"
 
-
 RenderPassData::RenderPassData()
 {
    reset();
@@ -394,7 +394,7 @@ void ProcessedMaterial::_setStageData()
             
             // Load a debug texture to make it clear to the user 
             // that the texture for this stage was missing.
-            mStages[i].setTex( MFT_DiffuseMap, _createTexture( "core/art/missingTexture", &GFXDefaultStaticDiffuseProfile ) );
+            mStages[i].setTex( MFT_DiffuseMap, _createTexture( GFXTextureManager::getMissingTexturePath(), &GFXDefaultStaticDiffuseProfile ) );
          }
       }