Intermediate Nodes with custom state data do not overwrite `copy()` method

[fastbodin]

Nodes include: LinearProgramNode, IsInNode, QuadraticModelNode, PermutationNode, AdvancedIndexingNode, BasicIndexingNode, WhereNode, MatrixMultiplyNode, ReduceNode, ArgSortNode, NaryOpNode, BroadcastToNode, ReshapeNode, AccumulateZipNode, ArrayValidationNode, and DynamicArrayTestingNode.

It just so happens that none of these nodes are ever copied so this is not necessarily an issue per se. This came up when trying to diagnose issues on NumberNode after adding a custom NodeStateDate (3b10b41). Currently, if these nodes were copied, the copy would be filled with junk data.

Possible Solution: Add an override copy() method to all and add a copy() test on the ArrayValidationNode?

[arcondello]

Would it make sense to limit the copy() method to only the decision nodes?

[fastbodin]

That seems like a simpler fix. I believe it will be worth checking whether there any of the intermediate nodes that have a _from_symbol() method at the Cython level.