More honest output if a transform is deleted because it has been removed from disk
Added pipeline for cleaning up dead nodes
Expanded tests
Place InputTransform meta data at the imageset level for assembled images.
Images have InputTransformHelper base class added for use in stos functions.
BuildImagePyramid was not building downstream images when the source image was updated.  Added a check to delete the downstream image if the source image was newer.

Delete masks that have dimensions which do not match the source image in assemble
Fixed reversal of height width in dimension checks for cropboxes
Fixed test bug
Fixed check for mask dimensions when original image did not exist
Merge branch 'dev'

Conflicts:
	nornir_buildmanager/operations/reporting.py
Test fixes
Merge branch 'dev'