v2.4.1
Revert #3a81f60 for now

(with it some tests break and it can generate invalid output, see issue #44)
Add an exit code to the test suite

By adding the exit code 1 (or any other non-zero exit code) `npm test`
will know the tests didn't perform correctly. This way it's easier to
know if pull requests are good or bad.
Merge pull request #322 from rvanvelzen/test-exit-code-1

Add an exit code to the test suite
Fix #280

The `init` of the `ForStatement` is not a `BlockStatement` before it was
descended. The descend has to happen first, and *then* the actual
checks.
Merge pull request #323 from rvanvelzen/undefined-drop-vars-fix

Fix #280