0025076: Hidden overloaded virtual functions

0025076: Hidden overloaded virtual functions

Implementation of virtual functions is made more consistent in places where warning was issued:

- Missing implementation of virtual method Closed() added in classes inheriting Intf_Polygon2d
- Empty implementation of virtual method Read() accepting stream is moved from PCDM_RetrievalDriver to StdLDrivers_DocumentRetrievalDriver
- Method BRepFill::Delete() is renamed to DeleteProfile() to avoid confusion with method Delete() inherited from MMgt_TShared
- Virtual method AIS_Dimenaion::ComputePlane() is removed from base class; each dimension defines and uses its own method with the same name (but different arguments)
- Inherited virtual method Dump() with single argument in class XCAFDoc_ShapeTool is now defined as short-cut to own method Dump(), also calling parent's one
- Inherited virtual method BoundingBox(void) is made visible in AIS_Shape
- Inherited virtual method Box(void) is made visible in classes inheriting BVH_PrimitiveSet