user/qpdfview: new package

Note that PS and DjVu support have been disabled until the following are
packaged:
* libspectre
* djvulibre

This is a new aport and can be submitted to Alpine as well.

See merge request !18

user/qt5ct: new package



See merge request !22

This also removes the compton-conf dependency, since at the moment we don't
actually ship compton.