add some examples demonstrating the construction of state machines

[exarkun]

The API docs are pretty good but some complete, runnable, explained examples would almost certainly make the library more easily approachable.

[exarkun]

Ideally the examples would come with automated test coverage. I know the one example machinist comes from doesn't work (it's only half written, after all, and depends on a a hardware control library that doesn't actually exist, and on top of that there's any mistakes I didn't notice while writing it, which are no doubt legion).

It would be cool to turn it into something that does work (perhaps not by trying to actually control real hardware, though; simply generating some output whenever the hardware would have been poked should get the point across) and to have test coverage proving this.

It would also be nice to have examples that focus on different areas of machinist - insofar as those areas can be separated. The functionality that can be derived from the rich input feature is an obvious candidate for a dedicated example or two.