Input and outputs dependent on vertex

[marcosh]

Currently a BaseMachine has type BaseMachine (topology :: Topology vertex) input output.

In practice we are allowed to specify a specific state space for every vertex of the topology, while the inputs and the outputs must remain constant throughout the whole machine.

It would be interesting to allow inputs and outputs to be dependent on the current vertex,

In practice, this would allow to specify for every vertex which inputs could be received and which outputs could be emitted