Deprecated Overlaps() methods have been moved from subclass SelectMgr_SelectingVolumeManager
to the base class SelectBasics_SelectingVolumeManager,
so that they are actually accessible within Select3D_SensitiveEntity::Matches() implementations.
Several methods have been marked as pure virtual in the base interface.
Second SelectMgr_BaseIntersector::OverlapsPolygon() has been dropped from virtual interface
as useless (trivially replaceable).
