fiat-crypto now generates proper types, so take advantage of that.
Add mixed subtraction and double base multiplication.
We will eventually leverage mixed addition/subtraction for fixed
base multiplication. The reason we don't right now is that
precomputing the tables at comptime would take forever.
We don't use combs for the same reason. Stage2 + less function
calls in the fiat-crypto generated code will eventually address
that.
Also make the edwards25519 code consistent with these changes.
No functional changes.
Functions generated by Fiat-crypto are not prefixed by their description any more. This matches an upstream change.
We can now use a single type for different curves and implementations.
The field type is now generic, so we can properly handle the base field and scalars without code duplication.