Where to put concrete types without abstract super type?

[SoongNoonien]

Since #2391 is merged, we now have two different places where concrete types are defined which don't have a corresponding abstract super type. The Puiseux polynomials are under AbstractAlgebra.Generic while other types like the universal rings or MatSpace are directly under AbstractAlgebra.
I would think that the Puiseux polynomials should be moved to AbstractAlgebra as well. I had mentioned it here, but since nobody responded I forgot about it as well until #2391 was merged.

[lgoettgens]

I am not sure if this is a good question for triage (unless to remind people to later have a look at this).

If @thofma and/or @fingolfin could just comment their opinion here, this would already help.

[fingolfin]

I'd be fine with moving them out of Generic.

My rule of thumb always was this:

• if a construction is "universal" (as in: we expect to only need the one), it lives directly in AA
• if a construction is "generic" (so it can be used as implementation on any ring, but we may wish to provide additional, specialized implementations), then it goes into AA.Generic.

So that fits nicely here.