Add Ringbuffer interface an 2 implementations, synchronized (locking) SyncedRingbuffer and lock-free LFRingbuffer.

SyncedRingbuffer is moved from JOGL to GlueGen, and generalized w/ common interface Ringbuffer
to allow testing diff. implementations.

- Added Ringbuffer.AllocEmptyArray factory interface, allowing to pass a constructor
  to construct the generic array.

- Added functionality is growBuffer(..), allowing to either grow a full or empty buffer,
  using Ringbuffer.AllocEmptyArray.

- Removed explicit 'clearRef' at get*(..), always clear the taken reference for better
  interface generalization.

- Added LFRingbuffer, exposing lock-free get*(..) and put*(..) methods
  using the 'Always Keep One Slot Open' pattern using the read/write index as barriers only.

- Ctor's copy an optional passed user array into the internal array,
  utilizing Ringbuffer.AllocEmptyArray.

- Added unit tests.