I'll pick one of the open source licenses once the project is more useful.

I'd recommend checking out the API Guidelines for some thoughts on this. The default recommendation if you don't have another preference is MIT + Apache 2.0

https://rust-lang.github.io/api-guidelines/necessities.html#...

Thanks! Apache 2, MIT or BSD, please. ;)

The standard implementation does not have debug mode. Reverse engineering GV by reading the 90's style c code is not fun either.

Sure it is