GitLab

Backports nifty8 -> nifty7

See merge request !663

Otherwise it cannot be run on other machines

Make the colorbars nicer and adapt their size to the 2D plots canvas

See merge request !660

Remove gitversion interface, docs improvements and workaround pip

See merge request !657

Add pypi related files and rework documentation

See merge request !654

The reason is that the README is shown on PyPI and this information is
not really relevant for an enduser since she can just look at the
official documentation.