Avoid double loading of featured materials

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35921 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Styling spreadsheet, styling of properties for spreadsheet, changed icons in properties stylebar

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35922 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
#4208 Basic layout (toggling statistics/data/second plotpanel views) works.

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35923 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e