prevent NPE
Merge branch '8.36' of ssh://dascgitolite@dasc-git.diamond.ac.uk/gda/gda-core.git into 8.36
don't fail if two scannablewriters try and write the same item

both will overwrite the data from each other, but that's only a problem if they don't match
allow comonent name to be null (for data that has no @local_name equivalent)
conditionally write elements in NXsource when cofigured

otherwise it may clash with information put in by ScannableWriters
(Silvia has that problem)
Merge branch '8.36' of ssh://dasc-git.diamond.ac.uk/gda/gda-core into 8.36

Conflicts:
	uk.ac.gda.core/src/gda/data/scan/datawriter/scannablewriter/DefaultComponentWriter.java
Merge branch '8.36'