Log message:
Mark packages as not ready for python-3.x where applicable;
either because they themselves are not ready or because a
dependency isn't. This is annotated by
PYTHON_VERSIONS_INCOMPATIBLE=  33 # not yet ported as of x.y.z
or
PYTHON_VERSIONS_INCOMPATIBLE=  33 # py-foo, py-bar
respectively, please use the same style for other packages,
and check during updates.

Use versioned_dependencies.mk where applicable.
Use REPLACE_PYTHON instead of handcoded alternatives, where applicable.
Reorder Makefile sections into standard order, where applicable.

Remove PYTHON_VERSIONS_INCLUDE_3X lines since that will be default
with the next commit.

Whitespace cleanups and other nits corrected, where necessary.

Log message:
Drop superfluous PKG_DESTDIR_SUPPORT, "user-destdir" is default these days.
Mark packages that don't or might probably not have staged installation.

Log message:
Remove python24 and all traces of it from pkgsrc.
Remove devel/py-ctypes (only needed by and supporting python24).
Remove PYTHON_VERSIONS_ACCEPTED and PYTHON_VERSIONS_INCOMPATIBLE
lines that just mirror defaults now.
Miscellaneous cleanup while editing all these files.

Log message:
Let's assume for now that everything that worked with python-2.6 also
works with python-2.7.

Log message:
Import py26-oasa-0.13.1 as wip/py-oasa.

OASA is a free cheminformatics library written in Python