Lightweight VectorArray implementation

[mikera]

It should be possible to create a non-canonical Vector implementation that wraps Cells directly in a Java Array.

Objectives:

• Lightweight, better performance for short-lived CVM vectors and less GC pressure
• Allow O(1) slicing with array offsets
• Allow O(1) wrapping of argument arrays
• Should not affect CVM-visible Vector semantics in any way
• Should convert to regular Vector implementation when required (persistence, encoding etc.)