0026377: Passing Handle objects as arguments to functions as non-const reference to base type is dangerous

Operator of cast to non-const reference is declared deprecated to produce compiler warning if used (usually implicitly).

OCCT code is updated to avoid that cast, occurring when function accepting non-const reference to handle is called with handle to derived type.
For that, local variable of argument type is passed instead, and down-cast is used to get it to desired type after the call.
A few occurrences of use of uninitialized variable are corrected.

src/OpenGl/OpenGl_View_Raytrace.cxx

@@ -1589,8 +1589,9 @@ Standard_Boolean OpenGl_View::initRaytraceResources (const Handle(OpenGl_Context
 // function : nullifyResource
 // purpose  :
 // =======================================================================
+template <class T>
 inline void nullifyResource (const Handle(OpenGl_Context)& theGlContext,
-                             Handle(OpenGl_Resource)&      theResource)
+                             Handle(T)& theResource)
 {
   if (!theResource.IsNull())
   {