Toolbar icon changes

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35817 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Fix for undefined index exception

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35818 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Use Steffi's new icons in desktop

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35819 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Resume 3D renderer any time a view is shown or hidden

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35820 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Slight speedup for spreadsheet

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35821 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e