fixed: #3734 (web: Add "Object properties" menuitem for context menu.)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@29442 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
#3728 more robust

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@29443 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
allow loading base64 .ggb files from 4.2 Chrome App

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@29446 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e