OpDataSelection: Extra assertions.
DataSelection: Disable 0.5 import for now.
Dataset table: context menu: disable 'edit' option if dataset hasn't even been chosen yet.
DataSelection: Serializer supports new multi-dataset scheme. (Importing from 0.5 not supported yet.)
DataSelection: Serializer: Fixed dirty status after deserialization.
DataSelection: Tables show row numbers.
DataSelection: Added nickname field.  Save axistags as a dataset info field.
DataSelection: Fix serialization of axistags settings.
Dataset Properties Editor: Support selection of channel display settings.
dataset properties editor: Don't show internal path as part of link path.
DataSelection: Gui: Show selected dataset now matter which table you're using, use role names as layer names.