#3299 Barebone for Login and LogOut functionality client side

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26170 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Ticket #3407: use positive numbers for denoting RGB colors (in String), but support the older format still, too

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26171 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e