Expose python types of vector dual numbers

[prehner]

This PR exposes the python types of all vector dual numbers that are generated in macros.

In addition to that some docstrings are cleared up and some additional cases are covered by the derive functions, e.g.:

x,y = derive2(1, [2,3])        # already possible
x,y = derive2([1], [2,3])      # new in this PR

and the error message is improved slightly.

[prehner]

Some particular recursive dual numbers are still required to progress in https://github.com/feos-org/feos/issues/92

[prehner]

On second thought, having to make changes to this repository whenever a new obscure dual number is required in feos is impractical. Instead we can expose the macro that generates the numeric operations.

[g-bauer]

I agree, it's easier to maintain if other crates just generate the needed python types.

[prehner]

I kept the vector dual numbers that are already built in the public interface to avoid having to build them twice.

With the impl_dual_num macro, feos or other libraries should be able to implement their own specific dual numbers in a couple of lines.