Add CATS compatibility for sample-transfer operations in the data collection
tree brick.
To be simplified (and made more pythonic) after switching to the new
GenericSampleChanger API with the SC3 at the ESRF. ;-)
Merge branch 'bessy_dev_cats' of https://github.com/hellmig/mxcube into hellmig-bessy_dev_cats

Conflicts:
	Bricks/widgets/dc_tree_widget.py
	HardwareObjects/queue_entry.py