GDA-5443 throw an interrupted exception where that is the cause of an
executionexception
GDA-5443 expose the attribute to return scannables to their original
positions at the end of a scan

The allows the flag to be overridden for specific scans.
fix bug where the value was not being saved between GDA restarts
Merge branch 'master' of ssh://dascgitolite@dasc-git.diamond.ac.uk/gda/gda-core.git