[Gui] Material, Appearance, make Chrome colour..

..lighter and therefore more realistic. See discussion on French forum https://forum.freecadweb.org/viewtopic.php?f=12&t=46581

src/App/Material.cpp

@@ -268,7 +268,7 @@ void Material::setType(const MaterialType MatType)
         break;
     case CHROME:
         ambientColor .set(0.3500f,0.3500f,0.3500f);
-        diffuseColor .set(0.4000f,0.4000f,0.4000f);
+        diffuseColor .set(0.9176f,0.9176f,0.9176f);
         specularColor.set(0.9746f,0.9746f,0.9746f);
         emissiveColor.set(0.0000f,0.0000f,0.0000f);
         shininess    = 0.1000f;
@@ -333,4 +333,4 @@ void Material::setType(const MaterialType MatType)
         transparency = 0.0000f;
         break;
     }
-}
+}