Allow parameters in Graph to be accessible from any node?

[pgleeson]

Should parameters listed in the Graph element be usable in (any) Nodes in the Graph? https://mdf.readthedocs.io/en/latest/api/Specification.html#graph

It seems to make sense that they would, so you can set a value once and use it in multiple nodes.

Would need to be implemented in here:

MDF/src/modeci_mdf/execution_engine.py

Line 999 in ca4843a

class EvaluableGraph:

and passed to every node (and edge?)...

@davidt0x Are there global parameters in PsyNeuLink models?