Better QVariant use detection
Fix no QMenu.triggered[QAction] signal overload in PyQt5

Replace with simple triggered as there is only a single signal, that
sends a QAction.
Replace QDesktopWidget.numScreens() with screenCount()
Port QWheelEvent usage in the ebook viewer
Port use of QVariant in the viewer, the viewer now basically works
Add note about testing viewer touch screen support on windows
Remove the workarounds for the Qt WebKit embedded font bug as the bug has been fixed in Qt 5