"reverse" edges / cycles / delay node

[straszheim]

implement reverse edges via "teleport/delay" node that hides the existence of the cycle from the ecto graph. delay node takes the default value for the output (and the number of timesteps delay > 0) as a parameter.

[straszheim]

duplicate of other cycles ticket... push to acrasidae

[ethanrublee]

Entangled cells exist for "feed-forward" style constructs. Closing for more specific features.