pyqt: Change install directories for Python flavor support
- PyQt could not be installed for multiple Python versions at the same time, as there were conflicting files.
This patch creates Python-version versioned directories for all these, and further installs binaries with a version number.
- Note, there might be some hickups for software that depends on on of the .so's provided by PyQt5, which might not be found anymore autmotically, and maybe need some LD-flaggery.
- Update PyQt5 to 5.10.1
- Mark www/py-qt5-webengine broken. It is unforuntately no longer compatible with the old qt5-webengine-5.9.4 we ship.