BUG: Changing sign for the radiative flux for the wallHeatFlux FO.

NOTE: The radiative flux (qr) is positive when the heat flux is going into the wall,
this is oposite the the he flux which is positive going out of the wall.

src/functionObjects/field/wallHeatFlux/wallHeatFlux.C

@@ -85,7 +85,7 @@ void Foam::functionObjects::wallHeatFlux::calcHeatFlux
 
         forAll(wallHeatFluxBf, patchi)
         {
-            wallHeatFluxBf[patchi] += radHeatFluxBf[patchi];
+            wallHeatFluxBf[patchi] -= radHeatFluxBf[patchi];
         }
     }
 }