kajongg has new dependencies

[Wolfgang Rohdewald]

master now requires

Python 3.5
python3-twisted 16.0
python3-pyqt5
python3-pyqt5.qtsvg

pyqt4, pykde4 and python2 will not be supported anymore

pykde4 is unmaintained and does not work with kajongg
anymore, see kde bugs 333683, 370998, 228016, 253123.

I will make use of python kf5 bindings when they are available.

with no kde bindings, kajongg still works but its GUI
has a few options missing like changing language, and
it might not always behave exactly as a KDE application.

Now I tried to adapt CMakeLists.txt but this is not complete.
Maybe somebody with more knowledge about cmake can
finish this.

Known open problems:
    - how to require minimum python3.5?
    - how to require minimum twisted 16.0 for python3?
    - eliminate private copy for PyQt5 in cmake-modules
    - the pykde4 module should not be used, or should it? kajongg does not 
use pykde4 anymore

-- 
Wolfgang