GDA (8.34.GDA-5863) Fix concurrent modification error in JythonServerFacade caused by by unsubscribing as a listener while updates are being sent out.

(Not an elegant fix)
GDA-5836 (8.34) Provided yaxis property on wrapped scans to set yaxis

Required as a work around because Scans within in scans do not set the user listed scannables correctly, and I had no time to wade in. Also a useful functionality though!