make the version a variable

[nyxnor]

I imagine you replace on every new release across the menus the version from previous to new.
If you put a version.txt and source it or a variable inside torbox.lib, then it will avoid outdated menu version when testing new releases as on #119

[radio24]

That's a good point. However, at the moment, it is labelled as v.0.4.2 because, so far, we do not have an official release.