GitLab

See:
https://github.com/matthew-brett/multibuild/issues/24#issue-221951587

Functions renamed to match their intent better.

The syntax is similar to how TravisCI does it.

Travis test uses `get_macpython_enviroment` for CPython and
`get_python_enviroment` for PyPy.

Aliased PYTHON_VERSION to MB_PYTHON_VERSION.

Changed the test command to use get_python_enviroment instead of
get_macpython_enviroment.

Extended TravisCI matrix to cover PyPy.
The tests can now tell the implementation of PyPy apart from the CPython
version they emulate.

pip will copy the directory it installs from before running the install
/ wheel build.  If the directory is a submodule, then the copy breaks
the connection with the containing project, so git commands to get the
version will fail.

Fix is to re-create the .git directory for submodules.

Version of fix in https://github.com/matthew-brett/multibuild/pull/12
with thanks to Hassan Kibirige.

For getting versions from versions with suffixes.