UI scaling

A good amount of stuff’s changed outside of the terrain editor, but the only relevant thing here is the UI scaling. The program still looks better / is most readable at 1600x900 because I did it “the wrong way” but if you’re using this on a smaller display than that the buttons should at least detect being clicked on now.

I also have a sudden desire to revisit the lighting system and some other things now, since I’ve been having so much fun doing lighting in other things lately. Soon, I hope.