Error recovery and continuation

[cdiggins]

The next big thing for Myna will be partial recovery from errors, so that multiple errors can be detected in the code. See: http://duriansoftware.com/joe/Constructing-human-grade-parsers.html.

Basically I see special rules to indicate where to advance to in the case of an error, and returning an array of errors from a parse (empty array indicating success).