allow f==c for Function, Line

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@37819 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
remove debugging

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@37820 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e