the revision 5 and 6 encryption algorithms specify the presence of additional encryption material named 'oe' and 'ue'. it turns out this is not always required so will now default to null if not present. this also adds support for those values being in hex rather than normal string format.
tidies up some commenting on the xynode class, moves public methods below constructors and adds xy to the resharper list of abbreviations for the solution.
