Derive `Hash` for all types

[benluelo]

Would be very handy to allow for them to be stored as keys in Hash{Map,Set}s.

[ahl]

In addition to Hash I think you'd need Eq which can't be derived in particular because NumberType contains f64s that don't implement Eq. I'm planning on closing this in the next few days, but even if you get back here and it's closed I would invite comments or suggestions to satisfy your use case. If you don't get a response, feel free to open a new issue and my apologies if it seems like this was closed prematurely!

[benluelo]

you could use something like https://docs.rs/ordered-float/latest/ordered_float/ for NumberType, i don't think NaN is valid in an openapi spec anyways(?)

[ahl]

I think that equality issues aren't limited to NaNs