1. Optimize hirarchy display, use jQuery 2. Delete most icons files, use icons from CSS instead 3. Better range selection in logx/logy scale 4. Handle situation when CORS blocks access to request headers

Signed-off-by: Bertrand Bellenot <bertrand.bellenot@cern.ch>
Add icons in JSRootPainter.css file

Signed-off-by: Bertrand Bellenot <bertrand.bellenot@cern.ch>