backport_digest-v0.7 master

stream-cipher-v0.3.0 stream-cipher-v0.2.2 stream-cipher-v0.2.1 stream-cipher-v0.2.0 stream-cipher-v0.1.1 digest_v0.7.2 digest-v0.8.0 digest-v0.7.6 digest-v0.7.4 digest-v0.7.3 crypto-mac_v0.6.0 crypto-mac_v0.5.2 crypto-mac-v0.7.0 crypto-mac-v0.6.2 crypto-mac-v0.6.1 block-cipher-trait_v0.5.0 block-cipher-trait-v0.6.2 block-cipher-trait-v0.6.1 block-cipher-trait-v0.6.0 block-cipher-trait-v0.5.3 block-cipher-trait-v0.5.2 block-cipher-trait-v0.5.1