Converts the ad-hoc design of the Material Editor to utilize the same inspector interface as most everything else does.

- Overhauls the material editor to simplify and streamline the logic behind it since the inspector does most of the work
- Tweak a few order positions of materialdefinition fields to work better
- Sets AO, Rough and Metal channel fields to use an enum type for human readability
- Updates the MaterialPreview gui control to work with assetIds
- MatEd now supports setting of parent material to inherit from
- Creating a new material now can prompt selecting an existing material to inherit from
- Can now edit the mapTo value of a material in the matEd
- New standalone Composite Texture Editor window for convering AO, Roughness and Metalness maps in a material to an ORMMap
- Can also star the creation of a composite texture via RMB context menu in AB on an image asset
- Moved logic of CubemapEditor from MatEd to it's own stuff
- Made ImageAsset fields now be more clear when they have nothing assigned, and also have a clear button to empty the field's value so it's consistent across the board
- Reorganized the layout of the gui and image files for the MatEd to be easier to navigate
- MaterialEditor now overlays the EditorGUI instead of being forcefully embedded in it, allowing easy editing of the MatEd Gui via the Gui editor

Engine/source/T3D/guiMaterialPreview.h

@@ -28,6 +28,8 @@
 #ifndef _GUIMATERIALPREVIEW_H_
 #define _GUIMATERIALPREVIEW_H_
 
+#include "assets/ShapeAsset.h"
+
 #include "gui/3d/guiTSControl.h"
 #include "ts/tsShapeInstance.h"
 
@@ -50,8 +52,11 @@ protected:
 
    MouseState  mMouseState;
 
-   TSShapeInstance*  mModel;
-   TSShapeInstance*  mMountedModel;
+   DECLARE_SHAPEASSET_REFACTOR(GuiMaterialPreview, Model)
+   DECLARE_SHAPEASSET_REFACTOR(GuiMaterialPreview, MountedModel)
+
+   TSShapeInstance*  mModelInstance;
+   TSShapeInstance*  mMountedModelInstance;
    U32   mSkinTag;
 
    // For Camera Panning.