Mark as not ready for python-3.x.
While here, slightly clean up Makefile and fix conflict with itself
by adding ${PYVERSSUFFIX} to pymol binary.
Bump PKGREVISION.
Add standard comment to not-ready-for-python line.
Updated biology/py-mol to 1.5.0.1nb3
dd REPLACE_CSH. Bump version.
Updated pkgtools/pkglint to 4.136