Add more methods from `num_traits::Float`

There are a couple of occasions where I regularly have to add an additional `num_traits::Float` bound.

Methods I need from `num_traits::Float` include the following:
- `min_positive_value`
- `is_nan`
- `nan`
- `infinity` and `neg_infinity`
- `max` and `min` with the `NaN` semantics
- `copysign`

Is the `RealField` suitable for these methods or is it intended to be more abstract, i.e., it not necessarily represents these floating point semantics?