- added 1 more successful test vectors.
now there are 8 test vectors[test vectors 0..7].
- test vector 5 has optional message
- test vectors 5, 6, 7 have G=GENERATOR
Both generating and verifying a proof allows for specifying a custom
generator point G. But that custom generator point was not passed into
the dleq_challenge function, resulting in the default (secp256k1)
generator point to be used. This lead to the test vectors being
incorrect.