Port our Qxt fork to Qt5

There was no Qt5 release of Qxt yet, so we have to always use
our fork. It has been ported to build against Qt5, but was not
tested yet.
Disable plugins for now
Port and clean up CMakeLists.txt
Build TepSonic against Qt5
Port and enable all plugins
Remove moc includes from .cpp files

CMAKE_AUTOMOC now does the hardwork for us
TODO
Update README
Bump version to 1.60.0

This is a new era for TepSonic. Project is alive again, it's ported
to Qt 5 and it has a bright future again. Let's skip 1.0 release
and go right for 2.0
Merge branch 'qt5'