semver: One module C library, author expects to use clib for installation. No packages.
Shiny: no packages
poly2tree: Obsolete, candidate for removal
polypartition: Obsolete, candidate for removal
Header only
igl
nanosvg
agg
catch2: Only Arch has packages for catch2, other distros at most catch (v1.x). Being strictly header only, we bundle this in the source tree. Used for the unit-test suites.