Store undo points if somebody is listening (needed for Smart, ppt)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@33948 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Make sure invalid toolbar string does not kill GeoGebra

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@33949 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e