MM compatibility issues

[m4rc1e]

Hey,

If I attempt to generate the family using newer versions of fontmake, it flags many incompatibilities. If I disable fontmake's compatibility checker, the i variants don't seem to interpolate.

If you're able to fix these, I'll push an update to this repo with a new build chain.

[chrissimpkins]

Any updates here?

[chrissimpkins]

Checking in again to see if there are any updates here?

[m4rc1e]

@chrissimpkins no updates on this one I'm afraid.