Translate maps directly

Instead of translating the messages of the maps in the single kgeography catalog, store the translations directly in the maps, loading them from there. This has few advantages:

• each map carries its own translations, which makes it easier to load and distribute; this eases the possibility to ship translated maps via GHNS, or to provide own maps properly translated
• the kgeography catalog now contains only the hundred of so messages for the GUI

To do so, we use itstool to both extract the messages, and merge them back in the XML files of the maps; the locales that itstool writes are BCP47, so we need to map our list of configured UI languages to these. Another change is the translation workflow: now there is a catalog for each map named kgeography._map_.<mapname>: considering there are 153 maps at the moment, that means 153 new catalogs. I preferred this over other solutions to keep the workflow easier, and have the possibility to easily translate a map at a time, and to distribute the work to more people.

@aacid in case we decide to get this in, please do not merge it (approve only) and let me do it, as there are few things to do before:

• we need to get itstool 2.0.6 on scripty, as older versions do not support -i/--its in join mode; it is easy to backport though
• I will split the current kgeography translations into the various map catalogs before scripty runs, so all the translations are preserved