0.2.2.2

* Add the ability to percent-encode directly into a Utf8Builder.
* Add Utf8Builder.unsafeAppendBufferBuilder.

0.2.2.0

* Add the ability to encode custom types as JSON keys

0.2.1.0

* Fix a buffer overrun in the double serializer
* Add support for URL percent-encoding
* Tweak the BufferWriter struct to improve code generation