In the past, translation files provided by the community
mostly came as pregenerated .qm files missing the corresponding
.ts sources. This has led to a situation where the translations
are out of sync with the sources and the sources have not been
updated for several release iterations.
To improve the situation, this commit syncs all .qm files back to
the sources by using the lconvert tool to create .ts files and
updating these files against our sources using lupdate.
For future updates, a CI solution would be preferable.
