The license

[tansiret]

I have seen that you have done several tweaks to change MIT's permissive nature. I think you need GPL because it already does what you want by itself and you can benefit from support of Free Software Foundation when you use a copyleft license like it.

[IanLunn]

Thanks for your advice here. Some others have already raised the issue and I'll look at moving to GPL with the next major release.