4.0.0

Changes to c.test:

• Breaking change: before a test passed if the check function returned anything other than false. Now, for a test to pass, the check function must return true - any other return value is considered an error.
• Add optional callback function.
• Allow for no-op tests (empty arrays).
• Add optional ms argument in the wait function passed to action, to retry every ms milliseconds until the condition is met or wait is elapsed.