Polyhedronnetconvex: Compute complete, with some bugs 

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@31239 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
#3947 Text tab works but preview doesn't on web
#3993 desktop fix 

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@31240 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e