Implement installing python programs from git.

[Poikilos]

Make it work whether the project uses setuptools or not:

• Make a run script in the path like this one generated by setuptools:

#!/usr/bin/python3
# -*- coding: utf-8 -*-
import re
import sys
from nopackage import main
if __name__ == '__main__':
    sys.argv[0] = re.sub(r'(-script\.pyw|\.exe)?$', '', sys.argv[0])
    sys.exit(main())

• Warn if setup.py doesn't say it is compatible with the os (Has a list of classifiers but doesn't mention Operating System :: POSIX, Operating System :: POSIX :: Other, Operating System :: Other OS, Operating System :: OS Independent, nor the current platform--see https://pypi.org/classifiers/)

Examples:

• https://github.com/poikilos/TemperatureTowerProcessor
• https://github.com/poikilos/blendernightly
• https://github.com/poikilos/BackupNow
• https://github.com/poikilos/scalerim
• https://github.com/poikilos/PolarBacteria
• https://github.com/poikilos/drawonboard
• https://github.com/poikilos/KivySpinningBunnies
• https://github.com/poikilos/blnk
• https://github.com/poikilos/lepidopterist