Cbit, a class for encapsulating computation

This is a monad which represents a computational bit, or cbit. It doesn't use the traditional terms that monads use. So, fork becomes run, etc.

The implementation is pretty much copied verbatim from the data.task class in the Folktale framework. Except the names have been changed to be more internally consistent, at the expense of consistency with the fantasy-land spec (for instance, orElse becomes rejectedChain). I've also stripped it to just the functions I found myself actually using, plus a function that doesn't exist in data.task (bichain). Lastly, I wrapped the very helpful Async.parallel function from control.async into this class, as Cbit.fromParallel.

The goal is to have a "Task" monad implementation which is simple, and has consistent methods and consistent naming. If a method exists for one side of the disjunction, it should exist for the other and have a similar name.

Licence: MIT