refactor ref_data to use RefCounted

[eh-jogos]

This is a "proposal" for a way to use ref_data with RefCounted objects instead of Dictionaries.

I think it will be a little bit easier to create new ones when you don't want to override a lot of stats, adds type completion when using it in code, and automates passing the data from UnitData to ActorStats, so we don't have to give it maintenance, just add the same property on both and it works.

[Snayff]

I've looked at this twice now and it isnt clicking for me. I'll pull the branch and play around locally, see if that does the trick.

[eh-jogos]

Just updated this PR rebasing it to curent develop and fixing some mistakes