Drop subtitles from settings dialogs (Fixes #239)

The subtitles don't add much to the value to the dialog, take up extra
space in the window decoration (while at the same time being squeezed
in) and oftentimes actually contained pretty much the same string as the
window title.
2 jobs for !38 with remove-subtitles in 2 minutes and 59 seconds (queued for 3 seconds)
merge request