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.