add App.copyBase64ToClipboard()

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26257 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
removed dialog to change worksheet title, instead direct manipulation is possible (gui design pending).

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26258 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e