v0.9.0

[tony-iqlusion]

Diff from 0.8

• Remove redundant "namespacing" from type names #112 Remove redundant "namespacing" from type names.
• Move 'curve' module (back) under 'ecdsa' #111 Move curve module (back) under ecdsa.
• signatory-yubihsm: Upgrade to yubihsm 0.18 #110 signatory-yubihsm: Upgrade to yubihsm 0.18.
• Use 'subtle-encoding' crate for constant-time encoding/decoding #109 Use subtle-encoding crate for constant-time encoding/decoding.
• ECDSA secret key types and traits #108 ECDSA SecretKey type and related traits (e.g. GeneratePkcs8).
• Properly handle leading zeroes in ASN.1 serialization/parsing #106 Properly handle leading zeroes in ASN.1 serialization/parsing.
• signatory-yubihsm: Expose the yubihsm crate as a pub extern #105 signatory-yubihsm: Expose the yubihsm crate as a pub extern.
• encoding: Use 0o600 file mode on Unix; comment improvements #102 encoding: Use 0o600 file mode on Unix.
• Eliminate ed25519::FromSeed trait #97 Eliminate ed25519::FromSeed trait.
• yubihsm: NIST P-384 support #94 yubihsm: NIST P-384 support.
• ring: NIST P-384 support #91 ring: NIST P-384 support.
• Add NIST P-384 elliptic curve type (closes #73) #89 Add NIST P-384 elliptic curve type (closes NIST P-384 ECDSA #73).
• signatory-yubihsm: Fix ECDSA over secp256k1 signing (closes #87) #88 signatory-yubihsm: Fix ECDSA over secp256k1 signing (closes Missing CurveDigest trait  #87).
• Provider ledger #80 signatory-ledger-cosval provider.
• signatory-yubihsm: Normalize secp256k1 signatures to "low S" form #79 signatory-yubihsm: Normalize secp256k1 signatures to "low S" form.
• signatory-secp256k1: Bump secp256k1 crate dependency to 0.11 #78 signatory-secp256k1: Bump secp256k1 crate dependency to 0.11
• Unify verification API under the Verifier trait #76 Unify verification API under the Verifier trait.
• encoding: Add encoding module with hex and Base64 support #74 encoding: Add encoding module with hex and Base64 support.
• Unify signing API under the Signer trait #70 Unify signing API under the Signer trait.