Log message:
lang/python26 has been removed. Remove other python versions here too like
31 and 32 which are not supported any longer.

Log message:
Remove pkgviews: don't set PKG_INSTALLATION_TYPES in Makefiles.

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.