BUG #14076: Fix undo/redo issues with multiblock properties.

Fixed the logic when updating block properties collectively. Ensuring that the
undo-redo sets are created for the entire operation and not individual steps.
Also fixed several other issues with the panel e.g.
- refreshing too much as properties change.
- when a property was changed, it cause the ui to change the property again,
  causing undo/redo to not work as expected for block visibilites.

Change-Id: I0ad032d13e83fbbd2ac9c1082c5c428bec5d12d1
Merge topic '14074_fix_undo_redo_issues' into next

a764d41 BUG #14076: Fix undo/redo issues with multiblock properties.