2.0.0 RC3

This is a release candidate for Amp v2.0.0. Please test it carefully and provide any feedback you have.

• Added isRequested() and throwIfRequested() methods to CancellationToken.
• Fixed issue in UvDriver where certain conditions could cause an error to be forwarded to the loop error handler whereas the callback was simply invoked by other loop implementations.
• Modified Coroutine to handle immediate continuations (i.e.: yielding a succeeded promise) iteratively instead of recursively to avoid deep call stacks.
• Added option to set the class name of the auto-created loop driver using the environment variable AMP_LOOP_DRIVER.
• Fixed issue where repeat watchers with interval = 0 could block the loop. Repeat watchers are now executed a maximum of once per loop tick.