Host settings using Qt.labs.settings

git-svn-id: http://cantata.googlecode.com/svn/trunk@5290 b1e49159-3266-923f-9c3e-04f16369770a
Fully migrate the settings to Qt.labs.settings

git-svn-id: http://cantata.googlecode.com/svn/trunk@5291 b1e49159-3266-923f-9c3e-04f16369770a