Improved SimpleTestCircuit

[tilk]

This PR changes SimpleTestCircuit so that Adapters and TestbenchIOs can be automatically constructed for required methods. Type annotations is used to distinguish required methods from provided ones. Based on #30.

[piotro888]

Great!
Should we now shift from accepting external Methods in __init__ to using Required + connectors everywhere?

[piotro888]

related issue: #12

[tilk]

Great! Should we now shift from accepting external Methods in __init__ to using Required + connectors everywhere?

I don't see how connectors fit into this, could you elaborate? My original intention was to use proxy to satisfy dependencies, like this:

c1 = ProvidesSomething()
c2 = RequiresSomething()
c2.required.proxy(c1.provided)

(If this use case becomes standard, then proxy is a weird name and renaming is probably in order.)

I don't know if it is worth it to do a massive refactor now (but maybe it is?). There are also places where having method arguments seems useful (method transformers?). For now, let's try to use this and see where it takes us.