Add py__package__ to the ModuleWrapper, which makes relative imports easy to implement and fixed a lot of other things.

test/completion/imports.py

@@ -119,8 +119,7 @@ def test_import_priorities():
     See also #536.
     """
     from import_tree import the_pkg, invisible_pkg
-    # TODO currently not enabled, later we should actually fix this.
-    ##? int()
+    #? int()
     invisible_pkg
     # The renamed invisible_pkg in that module (look at ``__init__.py``!)
     #? float()