Ecru 0.2.0

It's been a bit longer for this release.

The major new additions are message buffering on eventual references and the Ref.whenResolved and Ref.whenBroken methods, as well as the __whenMoreResolved Miranda method. Along with eventual sends and the vat support from the previous release, this is enough to provide support for the when syntax sugar. The Python interface now can control the E event loop: ecru.api.iterate runs a single item in the queue of the vat exposed to Python, and ecru.api.incrementalEval queues an E expression to be run, returning a promise to Python immediately. There's an example IRC-bot REPL in doc/examples/

Special shout-out to Eric Mangold (aka teratorn) for bugfixes and testing. Thanks Eric!