0024157: Parallelization of assembly part of BO

0024157: Parallelization of assembly part of BO

I. New features:
I.1 class BOPAlgo_ShellSplitter
The new class BOPAlgo_ShellSplitter has been added.
Purpose:  The class provides the splitting of the set of connected faces
	on separate loops

II. Changes:
II.1. class BOPAlgo_BuilderSolid
- method:
void BOPAlgo_BuilderSolid::PerformLoops()
the changes that provide parallel run the ShellSplitter algorithm have been done.

- method:
void BOPAlgo_BuilderSolid::PerformAreas()
the classification the grows and holes has been done using
the algorithm of unbalanced binary tree of overlapped bounding boxes