Indicate type of object in collection.
Add visitor to select siblings.
Select the siblings when an image of a MIF is selected.
Use Set instead of List.
Fix multi-selection and highlight of MIF.
Highlight node when multi-selection happens in tree.
Remove duplicated code to change color of the nodes.
Fix multi-selection issue in data manager tree (see #10855)
Add node-walking method to ImageTable.

This commit cleans imports and commented out code and adds a method
for highlighting TreeTable nodes that are part of a MIF.
Add missing comments.
Add method for changing colour in ImageTableNode.
Enable TreeTable node highlighting.
Implement rudimentary node highlighting
Remove unused method.
Fix MIF highlight in table view.