in order to make gufw installation process work, it includes itself
while installing. this raise the need that the build directory needs
to be a valid python identifier too. this commit solves this issue.
- python_module build style now builds modules for python2/3 by default
- new python2_module and python3_module build styles for building
python2-only and python3-only packages respectively
- no more python_versions
- no need to define pycompile_version for Python modules anymore
(still needed for non-Python modules though)
- Python version and paths are now guessed automatically and a set of
useful variables can now be used in templates
- #!/usr/bin/python2 and #!/usr/bin/python3 are now the default shebangs
- /usr/bin/foo2 and /usr/bin/foo3 are now the default names for bin
scripts (for use with alternatives)
