The library allows for registering special handlers for specific types or fields. This is particluarly useful for overriding the way `Data` is encoded (since many approaches exist) or supporting encodings like EJSON or Q which extend JSON with special types encoded as objects with field names perfixed by dollar signs.

Not integrated into build system yet (but builds nicely with Ekam). I think this is going to need to be a separate library, e.g. libcapnp-json, because clearly a lot of Cap'n Proto users don't need it at all.

For the moment, this was written for use inside Sandstorm. There is no current need for a decoder, so I have not written that yet and have no immediate plans to do so. But it will be added before any official Cap'n Proto release, certainly. A simple recursive descent parser should be easy...

For portions currently copyright by Kenton (most of it), transfer copyright to Sandstorm Development Group, Inc. (Kenton's company).

The license change is practically meaningless, as MIT and BSD 2-clause are legally equivalent. However, the BSD 2-clause license is sometimes confused for its ugly siblings, BSD 3-clause and BSD 4-clause. The MIT license is more immediately recognizeable for what it is.

Rémy Blank and Jason Choy (the two non-trivial contributors) are on record as approving this change:

https://groups.google.com/d/msg/capnproto/xXDd2HUOCcc/gbe_COIuXKYJ

Require a colon before 'group' or 'union' except for unnamed unions as well as the legacy case of a named union with an ordinal (where the colon is optional).