0024742: Remove rarely used collection classes: Set

0024742: Remove rarely used collection classes: Set

Classes NCollection_Set and NCollection_HSet removed as unused (along with NCollection_DefineSet.hxx and NCollection_DefineHSet.hxx).

Classes TCollection_Set and TCollection_HSet removed (along with TCollection_SetIterator and TCollection_SetList nested classes).
Code previously using Set classes updated to equivalent use of Sequence (Adaptor3d and Visual3d packages) or TColStd_PackedMapOfInteger (BRepAlgo package).

In Adaptor3d_CurveOnSurface, calculation of continuity intervals refactored so as to build and store sorted sequence of reals, instead of collecting them to set, copying to array, and then sorting.