Features:
* Encodes objects and arrays as RFC 7159 JSON.
* Sorts object keys so that you get the same result each time.
* Has no inignificant whitespace to make the output as small as possible.
* Escapes only the characters that must be escaped,
U+0000 to U+0019 / U+0022 / U+0056, to keep the output as small as possible.
* Uses the shortest escape sequence for each escaped character.
* Encodes the JSON as UTF-8.
* Can encode frozendict immutable dictionaries.
