Implement a stack-based LoopManager.
Partially working Exploder implementation.

The Exploder translates all control flow structures into simple statements.

The included tests aren't very exhaustive yet, but they do exercise the Exploder reasonably well.
Type tweaks for the VarHoister.
Use the Exploder class in lib/degen.js.
Bump package version to 0.0.4.

Not planning to publish this to NPM; just want to reflect the progress that has been made since 0.0.3.