0024023: Revamp the OCCT Handle - gcc and clang

Adaptations for compiling with GCC 4.7 and 4.8:
- Construction semantics is used for Handle objects being initialized by const Handle objects of derived type, to avoid overload resolution error in GCC 4.7.
- Missing includes added.
- Fixed bugs related to misuse of direct casts of handle.
- Eliminate CLang warnings on uninitialized and unused variables, functions, and expressions

src/GeomliteTest/GeomliteTest_SurfaceCommands.cxx

@@ -644,8 +644,8 @@ static Standard_Integer convbz(Draw_Interpretor& di,
   Standard_Real Tol = Precision::Confusion();
   
   NbU = Draw::Atoi(a[2]);
-  if ( (Handle(Geom_Curve)::
-	DownCast(DrawTrSurf::Get(a[3]))).IsNull()) {	
+  Handle(Geom_Curve) aCurve (Handle(Geom_Curve)::DownCast(DrawTrSurf::Get(a[3])));
+  if (aCurve.IsNull()) {
     // Cas Surfacique
     NbV = Draw::Atoi(a[3]);
     if (n<4+NbU*NbV) {