Fix #177.

Mark any (re-)generated cube maps as needing to be re-cached.

korman/operators/op_image.py

@@ -179,6 +179,7 @@ class PlasmaBuildCubeMapOperator(ImageOperator, bpy.types.Operator):
         image.pixels = pixels
         image.update()
         image.pack(True)
+        image.plasma_image.texcache_method = "rebuild"
         return image