renderGGBElement gets a second parameter as a callback (part one :-))

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36424 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Allow context menu in AV for multiple objects

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36425 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e