scale-activity, improved the prompt to enter a value

It is now easier for the children to see that they have
to enter a value. Added also an OK button to validate.

Fixed the values displayed on the items when displayed
in kg we were displaying 1 0 kg instead of 1.0 kg
Added central america and oceania geography map.
Added missing installation of scotland map.
Updated POTFILES.in for geography map.
Removed unused file in scotland map.
Added missing file for geo_country scotland
Added missing scotland.
Better sub locale support in gc_locale_get_name

For example, a fr_CH locale was not proposing French
in the hang game activity.