- move more active properties into their collections:

scene.active_keying_set --> scene.keying_sets.active
  ...same for active_uv_texture. active_vertex_color, active_keyconfig, 

- move mesh.add_uv_layer() and mesh.add_vertex_color() into their collections
  also have them return the newly created layer and dont set the layer active.

  uvtex = mesh.uv_layers.new(name)
  vcol = mesh.vertex_colors.new(name)

release/scripts/op/uv.py

@@ -69,7 +69,7 @@ class ExportUVLayout(bpy.types.Operator):
     def _face_uv_iter(self, context):
         obj = context.active_object
         mesh = obj.data
-        uv_layer = mesh.active_uv_texture.data
+        uv_layer = mesh.uv_textures.active.data
         uv_layer_len = len(uv_layer)
 
         if not self.properties.export_all: