Improve vectors on the wires functionality

[slibkind]

Currently, the approach to allowing vectors on the wires is to have every wire carry a vector of the same length which is specified in the type parameter. This structuring has some downsides related to type checking and constructors of machines (see for example PR #112).

Specifying vector passing as part of the interface type, instead of as a type parameter for example, makes the hierarchy of interfaces clunky.

Finally, we would like to add support for vectors of different lengths along the wires.

[jpfairbanks]

@tylerhanks, here is an issue caused by poor support for bundling. The approach you are thinking of involving Cospan(Set/Naturals)would be very helpful in improving support for wires that carry vectors.