Blender: Let .normalScale be exported as array.

utils/exporters/blender/addons/io_three/exporter/api/material.py

@@ -199,7 +199,7 @@ def normal_scale(material):
     logger.debug("material.normal_scale(%s)", material)
     for texture in _valid_textures(material):
         if texture.use_map_normal:
-            return texture.normal_factor
+            return (texture.normal_factor, texture.normal_factor)
 
 
 @_material