Fix bad creation of pyramid/prism when regular basis with n < 3 vertices

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30884 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Fix for #3770

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30885 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e