DOM memory system

Internal notes on the COLLADA DOM memory system:

daeMemory system is supposed to be a class that manages the COLLADA DOM's memory from different heap pools.

It overwrites malloc and free.

All dae classes overwrite new and delete to use the daeMemorySystem's malloc and free.

This has never been fully implemented. It actually makes it harder to profile the DOM because many memory profilers replace new/delete and malloc/free with their own functions but since the DOM does that they don’t work.