Add a new entrypoint to simplify shell scripts

- handle git and mercurial as source or target
- add argument to indicate target branch
- add argument to specify target version system
- when pushing a new branch, also try the ancestor branches too rather than update on tip (was done when pushing to mercurial)
- add argument to set commit message on duplicated repository

 fix running python3.6 unittests

Colorizing the logs are done with an unique function for all possible usages.
Colorization is redone, with more colors used to ease browsing the logs.
Tests are added with the some sample logs.

Marabunta is not run when using do_tests.
Change how the tests are run with do_tests: modules not to be tested are installed, then modules to test are installed with test enabled. This fix the issues of installation tests that were not run previously.