Update EdDSA to last circomlib version

[arnaucube]

• Update EdDSA to last circomlib version
  • Compatible with circomlib version 0.3.0 at https://github.com/iden3/circomlib/commit/5935ac69df760437da84cc7fe9f4db3ead56d47b
  • Use blake hash precandidate (non-blake2b) for circomlib compatibility
  • Add circomlib testvector
• Change PrivateKey from BigInt to [u8;32], which lead to faster signature computation: (Benchmarks on a Intel(R) Core(TM) i7-8705G CPU @ 3.10GHz, with 32 GB of RAM)
  • Old:

    sign                    time:   [559.84 us 568.41 us 576.26 us]
    verify                  time:   [376.59 us 376.68 us 376.78 us]

  • New:

    sign                    time:   [383.85 us 390.31 us 396.44 us]
    verify                  time:   [371.33 us 376.06 us 381.19 us]

[arnaucube]

Merged directly through git