moved translations into new resource on transifex

the 'strings' resource on transifex was in the internal 'Android 1' format
instead of the more modern 'Android 2' format.

This according to transifex support caused some weird issues…

The only work around (apparently) was to create a new resource (now call
main-strings) and use that instead.

I hope we didn’t mess anything up in the process.

Let's be extra careful with the next release