{password,username}.value.{start,end}

[stuartpb]

Right now, a lot of "must" and "mustnot" rules are for "must begin with a letter" or "must not start or end with space" (and I'm pretty sure every instance of required[0].classes[0]: nonspaces has been a mistranscription of that last one).

It'd be cool to make value.start and value.end into contents-like structures describing rules about the ends of a value, as that generalizes pretty succinctly.

[stuartpb]

Putting this on v0.1.0 for being straightforward

[stuartpb]

Moving to v0.2.0 so v0.1.0 can be unblocked.