materials preview, featured materials panel and some preliminary search result UI

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23544 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Google Analytics moved to <head>

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23545 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e