Create PublicKey, PrivateKey and Keypair enum

I want to delete all calls to ed25519 module to replace them with PublicKey, PrivateKey and Keypair enumerations

mentioned in issue #78 (closed)

created branch 77-create-publickey-privatekey-and-keypair-enum

mentioned in merge request !62 (merged)

mentioned in commit 52afc05f

mentioned in commit 03b6bc9e

closed via merge request !62 (merged)

removed milestone