This is a requirement of OpenSCAD now, needed to update to a working nightly.

You an also see it on my cvsweb or anoncvs checkout:

https://cvs.afresh1.com/cgi-bin/cvsweb/mystuff-openscad/

$ cvs -d anoncvs@cvs.afresh1.com:/cvs co mystuff-openscad

Comments, OK to import?

Manifold is a geometry library dedicated to creating and operating
on manifold triangle meshes. A manifold mesh is a mesh that represents
a solid object, and so is very important in manufacturing, CAD,
structural analysis, etc. Manifold also supports arbitrary vertex
properties and enables mapping of materials for rendering use-cases.
Our primary goal is reliability: guaranteed manifold output without
caveats or edge cases. Our secondary goal is performance: efficient
algorithms that make extensive use of parallelization, or pipelining
when only a single thread is available.

• manifold-3.2.1.tar.gz (2K)