crc24 checksum, as used by OpenPGP checksum as specified in RFC 4880, section 6.1
- Supports io.Writer streaming interface
- Follows the example of hash, hash/crc32 and hash/crc64.
Originally extracted from https://github.com/golang/crypto/blob/4ba4fb4dd9e7f7ed9053fb45482e9a725c7e3fb4/openpgp/armor/armor.go#L48
Under MIT