OK, here are the scripts. Note that the new one is just a POC to demonstrate the new theme format I'm proposing, and there is no version using the theme format it makes. I'm not presuming acceptance of my suggestion, but since I was already scripting, it was too easy to just work backwards and do the second script. If there's interest in such a conversion, I'm not above helping with the code aspect.

There are also source images for both proposed and existing formats of the Default theme, as ripped from 0.13-5; I'm not guaranteeing pixel-for-pixel identical results, but the output (in existing format) is visually indistinguishable for sure.