use zscale

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@37026 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Update curve when view changed (not rotated)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@37027 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e