Use Dutch/Flemish province names in Flanders

[halcyon-gh]

This makes the province names more consistent since they are in Dutch in the Netherlands and in French in Wallonia and France.

[arkhometha]

Hi @halcyon-gh, thanks for the pull request. The way vanilla Victoria 2 names provinces is by having provinces/cities default to the English name for them. That's why a province like Livorno, in Italy, is called Leghorn in game. The same applies to the Low Countries - Charleroi isn't called "Charles the King" in English, but by their French name, so their French name is kept.
Overall, I'd like to keep this standard as it A) confusion because people will search for "Damascus" instead of Dimašq, B) consistency since everything is in English and C) the trouble that would happen if we had to change a province everytime it changed hands and the occupier spoke another language.

This rule is only broken in special cases such as places with several names, depending on the occupier (like Port Arthur) to give some flavour to these parts - it would be weird if the Japanese conquered "Port Arthur" and it was still called that. I've added your suggestions to the "localized names" start game options in commit be39d4e, so if you'd rather play with localized names for these provinces, it will be easy to do so.