Merge branch 'shadowswift_new' into 'master'
Voronoi tests work now. I think I added all missing files used by `SHADOWFAX_SPH` and `GIZMO_SPH` to `Makefile.am`. I have also introduced a tolerance for geometric tests in the 2D Voronoi algorithm, which fixes round off issues that caused `testVoronoi2D` to fail if compiled with optimizations enabled. This fixes #282. See merge request !325