Test on Python 3.3
Update Python module code

Now use Python 2.x readline.c from hg 2.7 branch (changeset ID
89084:6b10943a5916) and Python 3.x readline.c from hg 3.3 branch
(changeset ID 89085:6adac0d9b933), i.e. the latest module in each
branch. Patch these files to rename the extension from readline
to gnureadline.
Build against readline 6.2 (patch-level 5)

Also modify patch 005 to support all future versions of Darwin, thereby
avoiding automatic breakage every time a new version of Mac OS X is
released.
Prepare for release 6.2.5

Update changelog, clarify the change of package name in README and
bump version number in setup.py.