Migrate to vanilla upstream PythonQt from MeVisLab

[iakov]

All the main fixes must be upstreamed.
Wait for the following to be merged
MeVisLab/pythonqt#266 -- QMake build system improvements
MeVisLab/pythonqt#267 -- Memleaks
MeVisLab/pythonqt#265 -- .clangformat for unified code-style

Seems like a lot of work is done in MeVisLab/pythonqt#292 , track this too.

As soon as main fixes are upstream-ed, we have to re-factor/re-check .

Note

Leave this issue open and update the description to match current state. Leave comments to document the upstreaming and difference reduction process.

Note

The further development should be done in the forked repo in the dedicated branch that contains only the difference: https://github.com/trikset/pythonqt/tree/trikset