This crate provides generic data encoding functions. It is meant to
guarantee mathematical properties, to conform to RFC 4648, to be
efficient, and to give choice between allocating and in-place
functions. It also provides an exhaustive example with similar
functionality to the base64 GNU program. It supports common bases
(base2, base4, base8, base16, hex, base32, base32hex, base64, and
base64url) and custom bases (defined on the command-line by their
padding and symbols in value order).