switch to qt5
new build dependencies
unreleased qt5 build
work around https://bugreports.qt-project.org/browse/QTBUG-39859
make qet-orig-source more verbose
some refinements
move qt5
Merge remote-tracking branch 'origin/qt5'

Conflicts:
	debian/changelog
	debian/compat
	debian/control
	debian/copyright
	debian/docs
	debian/rules
	debian/source/format
	debian/source/options
	qt4/debian/changelog
	qt4/debian/compat
	qt4/debian/control
	qt4/debian/copyright
	qt4/debian/docs
	qt4/debian/rules
	qt4/debian/source/format
	qt4/debian/source/options
	qt5/debian/changelog
	qt5/debian/compat
	qt5/debian/control
	qt5/debian/copyright
	qt5/debian/docs
	qt5/debian/rules
	qt5/debian/source/format
	qt5/debian/source/options