Investigate exporting to other file formats based on triangle meshes

[hannobraun]

Fornjot already supports exporting to 3MF, so adding support for more file formats based on triangle meshes should be relatively straight-forward. There's already an issue to track exporting to STL (#154). There are probably other file formats worth exporting to. The objective of this issue is to figure out which those are, and open a more specific follow-up issue for each one.

Labeling as https://github.com/hannobraun/Fornjot/labels/help%20wanted, as I have no experience beyond 3MF and STL, and don't know which other file formats might be applicable. Feedback is very welcome!

Labeling as https://github.com/hannobraun/Fornjot/labels/good%20first%20issue, as this work is pure research and doesn't require any knowledge of Fornjot. It might be a good way to get your feet wet, if you want to get involved.

[hannobraun]

This issue is a bit vague, and it's unclear how much Fornjot would benefit from support for more mesh-based export formats right now. Added an entry for this to the feature wishlist. Closing.