Go implementation of the Ristretto prime-order group over Edwards25519

 Many cryptographic schemes need a group of prime order. Popular and
 efficient elliptic curves like (Edwards25519 of ed25519 fame) are rarely
 of prime order. There is, however, a convenient method to construct a
 prime order group from such curves, called Ristretto
 (https://ristretto.group) proposed by Mike Hamburg
 (https://www.shiftleft.org).
 .
 This is a pure Go implementation of the group operations on the
 Ristretto prime-order group built from Edwards25519. Documentation is on
 godoc (https://godoc.org/github.com/bwesterb/go-ristretto).