GDA-5445 - Removed a call to writeStringData
in testNXTomoEntryLinkCreator because that call is now part of the
makelinks method of NXTomoEntryLinkCreator.
Revert to earlier version of NXLinkCreator as h5py cannot read soft
links to current file.
Make HardwareTriggeredNXDetector implement HardwareTriggeredNXDetector
for use on ConstantVelocityScanLine
Log exception variable in logger.error
PositionGrabbingAdapter supports PositionCallableProvider
Report exception when logging error
Allow Callable from PositioncallableProviders to support NamedQueueTask

To prevent the single ExecutorService being swamped by callables from a
single scannable allow the callable to specify the executor service to
use.

Use a LinkedBlockingQueue for the broadcasterQueue so that its size does
not need to be known beforehand.
Create ExecutorServices in the MultithreadedScandataPointPipeline rather
than get them from NamedQueueTasks to aid resource management
Support detectors that return null in getExtraNames
Prevent Scannables being wrapped in ContinuousScanLine to allow the 
used of ContinuousScanLine within a multiregion scan
Add use of ContinuousScan with a MultiRegion scan
MultiRegionScan - set parent of child scans
Log exceptions seen in evaluateCommand
Merge branch '8.28'

Conflicts:
	uk.ac.gda.core/src/gda/device/scannable/PositionStreamIndexer.java
	uk.ac.gda.core/src/gda/scan/ScanBase.java