0024911: Avoid using virtual functions in NCollection classes

0024911: Avoid using virtual functions in NCollection classes

NCollection_BaseCollection class, relevant header files, and macro DEFINE_BASECOLLECTION removed.
Hence methods Assign() from other compatible (via inheritance of BaseCollection) collections are not available any more, as well as base Iterator class.

All methods of Iterator classes are made non-virtual, allowing their inline expansion for better performance.

OCCT-specific operators new and delete added to collection classes and removed from iterator classes.