All python specific stuffs have been removed from backends/python/.
Python3 backend will create a separate process to deal with Python
specific stuff to resolve a problem with symbols conflict between
Python2 and Python3 libraries.

Moving Python3 & Python2 specific code to separate folders. Fixing
spaces to make it closer to the current coding conventions.

REVIEW: 120561

DIGEST: Scilab backend ported to Qt5/KF5
DIGEST: All Cantor backends ported to Qt5/KF5
DIGEST: First version of Cantor port to Qt5/KF5 complete - need fixes and drop KDELibs4Support

DIGEST: R backend ported to Qt5/KF5

Analitza requires QT_NO_CAST_FROM_ASCII to be disabled, therefore
we also have to disable it here, if we are building the KAlgebra backend

DIGEST: Sage backend ported to Qt5/KF5

DIGEST: KAlgebra/analitza backend ported to Qt5/KF5

DIGEST: Maxima backend ported to Qt5/KF5

DIGEST: Lua backend ported to Qt5/KF5

DIGEST: Qalculate backend ported to Qt5/KF5

Conflicts below were solved.

Merge branch 'master' into frameworks

Conflicts:
	src/backends/python/pythonbackend.cpp
	src/backends/python2/python2session.cpp
	src/lib/expression.cpp

src/backends/python to be shared between the current
python 2 backend and the additional future python 3
backend.

DIGEST: Python 2 backend ported to Qt5/KF5

DIGEST: All panels and assistants ported to KF5