I added new features to the solidify modifier.
- Clamp with respect to angles
- New Manifold Solidify mode to solidify non manifold geometry into manifold geometry
The C code is roughly based on my temporary addon script at:
https://github.com/redweasel/manifold-solidify
It is rewritten though and a lot of bugs from the script are fixed.
Also the fix intersections feature isn't implemented yet, but I will
likely implement it sometime and add a new revision then.