Implement universal curve interface

[collinc97]

Currently, there are separate branches for each curve. There are many curves out there, so we should re-design to accommodate them without multiple branches.

[cag]

For reference, curves are:

• elliptic.Curves that can be found here.
• even more elliptic curves which can be found here
• Pairing friendly curves which can be found here
• Any ol crypto thing that is isomorphic to a finite vector field

[cag]

We're using kyber Group interface for this purpose.