GDA-5863 merge pause buttons on Jython Console UI into a single one
remove compiler warning
GDA-5038 clarify in Javadoc the difference between atScanEnd and atCommandFailure


 - if the scan is aborted using an InterruptedException then stop() is called on all Scannables (and Detectors) and the pipeline is shutdown
 - if an exception of any other type occurs in the scan then atCommandFailure() and then stop() is called on all Scannables and the pipeline is shutdown
 - if the scan is requested to finish early (new feature in GDA-5863), or completes normally, then atScanEnd() is called on all Scannables and the pipeline completes