Added randomized variant of encapsulated array to test
- Cleaned up primitive (and reference) array variants.
 - Chose to use int indexes instead of longs. All variants expose am int-indexed Java array with getArray(), and will continue do to so in order to allow full use of Arrays.* and e.g. System.arraycopy array utilities, so we'll stick with int indexes and avoid long indexes (for the near term at least).
 - Removed shallowCopy from ReferenceArray. Replaced uses with System.arrayCopy