bug fix (#3099): AlgoBarGraph was not updating its point list correctly

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23940 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
bug fix (#3099): AlgoBarGraph was not updating its point list correctly. [needs 4.2 backport]

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23941 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e