shell: Don't show "current view" menu for applets that don't show the current lane.
Fixes #383
DataSelection: ui models don't assume that dataset roles is always configured before the dataset group is resized.
BatchIoGui: Cleanup viewer guis on shutdown.
PixelClassification: Workflow: Provide correct file path slot to batch operator.
Fixes #368
Added a TODO.
wip
OpDataSelection: Ensure that the special 'Image' slot is NOTREADY if there are no images loaded.
OpDataSelection: Resize DatasetGroup immediately when DatasetRoles is set.
Batch: gui: Set 'Dirty' flag before setting up preview, to avoid making the output layer ready too soon.
Fixes #370
Batch gui: Use @threadRouted to ensure that the table is always updated in the gui thread.
Fixes #386
Pixel Classification: Added a constraint to ensure that the input images all have the same dimensionality.
DataSelection: Imported stack volume datasets use human-readable filePaths.