Improved delete logic
Merge branch 'master' of github.com:mxcube/mxcube

Conflicts:
	Bricks/widgets/dc_tree_widget.py
Better information message when using user group function
Using warning level instead of info
Only allowing multiple select actions on samples.
Removing some unused code
Making delete more efficient
Not using self.collect_hwobj.crystal_snapshots_enabled() anymore