Port new Fiber impl from Ruby to Java, for lower-level magic.

See faac06d for details on the implementation.
Fix Fiber#transfer in new impl.
Merge remote-tracking branch 'origin/master'
Safety fixes for new Fiber.

* Ensure SizedQueue has been loaded before constructing any.
* Do not allow NEVER object to leak out of Fiber logic.
Reformat properly.
Merge remote-tracking branch 'origin/master'