Correct setting of MCR_CACHE _VERBOSE in previous commit but also  comment out until Doug has time to address.
Latest attempt to sort out ROI's for multiple channels & images in OMERO
Allow for no ROIs found when loading segmentations from OMERO
Remove 'delete previous' option from saving ROIs - separate delete menu items are more flexible.
Fix 'delete segmentation' option.
Fix remove segmentations.