Just to follow up, I didn't forget the capsule thing. I just bumped
into the realization that a capsule is just a sphere-swept line.
Sphere-swept shapes can be handled particularly efficient because
smooth support mappings (used in GJK) can be avoided. So I would like
to implement a general support for sphere swept shapes, such that
things like capsules can be modeled through that. I'll keep you
updated.