Chroma keying and translucency

I’ve added both in my fork here. It adds support for a key color as well as cross-fading one screen to the next, fading logos in and out, and so on:

If anyone’s interested, I could sync the fork back, but I’d rather not touch the main code!

Why not create a pull request? I’m a big fan of writing new features as a branch and PR rather than committing straight to master/main