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/GeomPlate/GeomPlate_CurveConstraint.cxx

@@ -312,7 +312,7 @@ void GeomPlate_CurveConstraint :: SetProjectedCurve (const Handle(Adaptor2d_HCur
 //---------------------------------------------------------
 Handle(Adaptor3d_HCurve) GeomPlate_CurveConstraint :: Curve3d () const
 { if (my3dCurve.IsNull())
-    return myFrontiere;
+    return Handle(Adaptor3d_HCurve) (myFrontiere);
   else
     return my3dCurve;
 }