Have translation to Turkish, Dari and Farsi updated and check variables

[fzesch]

• check all strings whether they are still correct (original meaning may have changed)
• ensure that variable numbers are not translated, but remain, e.g. %(since)s

[DaniGr]

I have marked all English fields that contain variables with yellow using conditional formatting so translators can find them more easily when proofreading.
I have also instructed Turkish, Russian, Farsi/Dari and Arabic translator about them and asked them to update.