alter nomaterial asset to a) use an imageasset, and b) remove the .cs assumption

Templates/BaseGame/game/core/rendering/materials/NoMaterial.asset.taml

@@ -2,5 +2,5 @@
     canSave="true"
     canSaveDynamicFields="true"
     AssetName="NoMaterial"
-    scriptFile="@assetFile=NoMaterial.cs"
+    scriptFile="NoMaterial"
     materialDefinitionName="NoMaterial" />

Templates/BaseGame/game/core/rendering/materials/NoMaterial.tscript

@@ -1,6 +1,6 @@
 //--- OBJECT WRITE BEGIN ---
 singleton Material(NoMaterial) {
    mapTo="NoMaterial";
-   DiffuseMap = "core/rendering/images/warnMat";
+   DiffuseMapAsset[0] = "Core_Rendering:warnMat_image";
 };
 //--- OBJECT WRITE END ---