0.72.2

• Fixed Box creation with nested connected plugs. This allows the creation of Boxes with shader nodes with input connections.
• Fixed removal of nodules from nodes in the graph ui when Plugs are removed.
• Fixed InputGenerator bugs and added python bindings and tests.
• Fixed Group bugs involving dynamically generated inputs and undo (#179, #210, #302).
• Tidied up node menu labels.
• Renamed WriteNode to ObjectWriter and ReadNode to ObjectReader (#17).
• Fixed minimum height of ramp editor (#445).
• Fixed empty messages from ErrorDialogue.ExceptionHandler.
• Added popup error dialogues for file save failures (#449).
• Fixed context used by interactive render nodes.