prevent crash in CGAL nef3. fix #issue 410 . also deal w qmake bug re .h files
simplify nef polyhedron code. attempt to add test for bug
finish adding new test, add png for new test
Merge branch 'master' into issue410x
print errmsg for applyHull. add quotes around err msg in version check.
build bug fix
Merge pull request #554 from openscad/issue410x

Issue410x