[MapData] - IconScale attribute and global overrides about artemis

[kristofbolyai]

I just found a crucial thing we need global overrides for. We need to be able to add category and feature overrides, for many features to work:

• Clicking on waypoints to be marked
• TerritoryArea color overrides for resource generation/guild color
• Changing only a single map features settings, i.e. user wants to make the Detlas blacksmith iconScale bigger.
• Providing category overrides this way (for user settings)

Basically the idea is to be to not have any explicit "marked state" for a feature, rather, provide a way for us to apply overrides to features, that make them marked. That way, the feature itself can provide the color, and other settings for it's marker, but an override can enable/disable the feature being marked.