fix issue #235
Merge branch 'master' of github.com:openscad/openscad into issue235
Merge remote-tracking branch 'origin/master' into issue235
fix failing tests per comments on github, make slightly more robust
Merge branch 'master' of github.com:openscad/openscad into issue235
Merge branch 'issue235' of github.com:openscad/openscad into issue235
Last #235 fix: Don't return empty PolySets, as they will be interpreted as 3D object later, causing a mixed 2D-3D error
Merge pull request #663 from openscad/issue235

Issue235