BLXVIII-118 tidy up output to user
prevent deadlock when a scan is aborted during readout by also checking the ScanBase flag
prevent NPE
Merge branch '8.36' of ssh://dascgitolite@dasc-git.diamond.ac.uk/gda/gda-core.git into 8.36
make this Data Writer act like other, especially NexusDataWriter, by running extenders after main data file added to
change number output as it is misleading
BLXVIII-118 refactor after testing with hardware to get I18 faster raster working

- data was being read out too soon, or in incorrect order
- waitForReadoutCompletion was not waiting, so data being wiped too soon