Fix for #2374 (web: File/new doesn't clear all drawable.)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26549 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
source cleaning (#2374)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26550 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
GuiManagerD implements clearAbsolutePanels (#2374)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26551 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e