0024831: Make iterators of NCollection classes STL-compatible

0024831: Make iterators of NCollection classes STL-compatible

STL-compatible iterators returned methods begin() and end() are provided in collection classes from NCollection package.
NCollection_Array1::Iterator is redesigned to use pointer instead of index.
Iterators of Sequence, Array, and Vector are extended by new methods to iterate backwards.

Use of SortTools_QuickSortOfReal is replaced by std::sort() in a few places (where possible).