Documentation.

WORK IN PROGRESS.

A Rust wrapper for Duktape. Things to do before this is minimally useful:

• [x] Handle non-UTF-8 strings.
• [x] Call JavaScript functions by name.
• [x] Define functions.
  • [x] Call specified Rust functions from JavaScript.
  • [x] Return errors from Rust to JavaScript.
• [ ] Convert to use Encodable/Decodable everywhere.
  • [x] Convert parameters to use Encodable.
  • [ ] Replace Value with serialize::Json.
  • [ ] Convert return values to use Decodable.
• [ ] Add nice macros.
  • [ ] Provide macro for calling functions.
  • [ ] Provide macro for defining functions.