Properly handle languages created not as extensions, post 9.2.  Fixes #103.

  Third time is a charm.

 * pyrseas/dbobject/language.py (LanguageDict.query): Do not include
   languages wrapped by extensions in query.
 * tests/dbobject/test_{extension, language}.py: New or modified
   tests, courtesy of DVarrazzo.
 * tests/dbobject/test_function.py: Moved bug 103 test to
   test_language.py.