Submodules

[dgrnbrg]

These need to be updated. Currently, the :token of a port is unique per module, not module instance. This may or may not interact badly with the simulator (should check into this). Also, need to consider what the API looks like and come up with some example usages.

[dgrnbrg]

Now, in the simulator, module state elements are identified uniquely by their location in the hierarchy (path vector from the root).

Next, connect must be made to support inter-module connections. That will complete submodule support.

[dgrnbrg]

Data can now flow into and out of submodules in simulation.