Generalize Jacobian.v over all a.

The immediate motivation is BoringSSL's generic EC code is sadly stuck
with supporting arbitrary curves, including those where a <> -3, but it
may be more generally useful.

This makes the file slightly more general:

- It now proves that the addition formula works independent of a = -3.

- It proves a generic doubling implementation, based on
  http://www.hyperelliptic.org/EFD/g1p/auto-shortw-jacobian.html#doubling-dbl-2007-bl

- There's a place to stick in other specializations should someone want
  them. (I hear some folks are interested in secp256k1 for some reason.)

0 files changed, 0 insertions, 0 deletions