Last-minute wishes for the next map format

[Thrawn]

PS: it's too early to expect great particle emitters: I just enabled what was already implemented. But I'll try to add at least a usable steam emitter. But that's not a file format change, so it'll have to wait.

Particle emitters might be easier to use if you can rotate them like mapmodels. Presumably that would be a file format change, which is why I'm bringing it up.