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/Geom/Geom_Conic.cxx

@@ -25,7 +25,6 @@
 #include <Standard_Type.hxx>
 
 typedef Geom_Conic         Conic;
-typedef Handle(Geom_Conic) Handle(Conic);
 typedef gp_Ax1 Ax1;
 typedef gp_Ax2 Ax2;
 typedef gp_Pnt Pnt;

src/Geom/Geom_Surface.hxx

@@ -20,7 +20,7 @@
 #include <Standard.hxx>
 #include <Standard_Type.hxx>
 
-#include <Geom_Geometry.hxx>
+#include <Geom_Curve.hxx>
 #include <Standard_Real.hxx>
 #include <Standard_Boolean.hxx>
 #include <GeomAbs_Shape.hxx>
@@ -31,7 +31,6 @@ class Geom_UndefinedDerivative;
 class Geom_UndefinedValue;
 class gp_Trsf;
 class gp_GTrsf2d;
-class Geom_Curve;
 class gp_Pnt;
 class gp_Vec;