For the time being we don't support writing a description for those, preferring
having all details in the method's description.
Using self-closing tags saves half the lines, and prevents contributors from
thinking that they should write the argument or return documentation there.
Clean: remove duplicate and interior vertices (uses Bullet algorithm)
Simplify: modify the geometry for further simplification (uses VHACD
algorithm)
In the editor, single convex hull now uses the clean option.
Added a new editor entry to create a simplified convex hull, can be
useful for creating convex hull from highly tessellated triangle meshes.
