Switch Python to single script + Makefile tricks
Instead of relying on shebang to call Python correctly, move to a
single script (non-executable) plus Makefile tricks to build the
desired python invocations. This also allows overriding the Python
versions from the command line.
- [DH] python/null.py
- [DH] python/null.py26-s
- [DH] python/null.py27
- [DH] python/null.py27-o
- [DH] python/null.py27-s
- [DH] python/null.py32
- [DH] python/null.py32-o
- [DH] python/null.py32-s
- [DH] python/null.pypy
- [DH] python/null.pypy-s