Fixed MAGN-1963 Undo/Redo of Python node edit crashes Dynamo
Explicitly making "BasicInteractive.SerializeValue" an abstract method
Implemented SerializeCore/DeserializeCore methods for BasicInteractive class
Slight consolidation in BoolSelector class
Reimplemented SerializeCore/DeserializeCore for Double/IntegerSlider
Merge branch 'ChocoButter-2Become1' into UndoRedoFixes
Implemented "SerializeCore/DeserializeCore" methods for "DummyNode"
Clear In/OutPortData in DeserializeCore method so they don't accumulate
Added unit test cases for the DummyNode.DeserializeCore fix earlier on
Merge pull request #1218 from Benglin/UndoRedoFixes

This request fixes some defects related to undo