Fix textdomains for add-on maps

[Noordfrees]

Re widelands/wl_addons_server#26

[hessenfarmer]

tested it fot the map descriptions and it works fine. Found an issue in the former official maps where I raised a PR.
However if possible the Folder names pointing to the maps have the same name as the addon and should therefore be localized as well if possible. (this would be similar to the My_Maps folder which is localized.

[Noordfrees]

The folder structure is defined inside the add-on itself. But I can implement that a map add-on can specify a profile of localized folder names which will be used for localization.

[Noordfrees]

Okay now you should see localized directory names for the Formerly Official Maps at version 1.0.3

Edit: Needs testing under Windows to check I got the dirname magic correctly

[hessenfarmer]

will test as soon as the localization is in the PO files

[Noordfrees]

The strings are on TX now. Let me know when you've translated them and I'll trigger another sync then.

[hessenfarmer]

I just tested it and the Former Maps directory got translated correctly as it is the same sting already translated. So this is working now and should be good to go.

[hessenfarmer]

translation is done