Converted MenuSettings to Strings instead of relying on position integer...

This allows us to easily disable 'Closest stations' and 'Game fragments' linking closed source code (Google maps and Play items).
The patch prepares the inclusion of BeTrains into F-Droid (https://f-droid.org/about/). The idea is to delete the items from the array.xml such that no 'disabled' functionality is presented to the user.