Merged a pull request by merijn_v1: civilopedia fixes and arrangement adjustments, translatable labels, URV documentation, code cleanup
Initialization of cultural coverage now properly uses Firaxis code for coordinate to plot index translation which takes map borders and wrapping into account.
Covered plots are not updated on reset anymore, because that can lead to a crashes and performance loss because the update may be executed after loading or on city acquisition/destruction with not fully initialized cities. Instead, covered plots are initialized once per city in the init() method.
Implications on save game compatibility are unclear, but since mostly useless code executions were removed there should be no inconsistencies after loading an old save. The save should open in any case. Problems in existing saves that led to crashes will not be fixed by updating, though.