OO Refactoring

[alazzaro]

This is a placeholder for future code modifications to OO:

• [ ] use member functions instead of separation between types and functions for proper data encapsulation
• [ ] (Suggested by @dev-zero ) besides iterators for double-loops, you could also think of implementing functional style map/reduce functions taking as arguments function classes (similar to pre-C++11 function objects). This would permit efficient implementation on per-value operations without exhibiting the underlying storage structure at the expense of one function call per value (plus a bit more for the abstract class implementation)