Remove dependency on ``importlib`` for Py2.6 support (issue #49)
Doc updates: describe new version v0.12.1
Bump version for v0.12.1
Add failing test for issue #50: list(list([1, 2, 3])) != [1, 2, 3]
Fix for issue #50: list(list([1, 2, 3]))
Remove fast-path __new__ for newdict; add explicit comments for newbytes and newstr
_url_collapse_path was named _url_collapse_path_split

for older version of python 2.7
Merge branch 'master' into v0.12.x: Nicolas Delaby's patch (#53)

This restores Python <= 2.7.3 support (#53)
Add (failing) tests for the resurrection of % formatting for bytes (PEP 461)

See feature requests #54 and #55