Material names are stored once in material.name, then duplicated in "additionalValues" This patch prevent this duplication

diff --git a/tiny_gltf.h b/tiny_gltf.h
index d1d22e7..1c2f1fd 100644
--- a/tiny_gltf.h
+++ b/tiny_gltf.h

@@ -3457,7 +3457,9 @@
     } else {
       Parameter param;
       if (ParseParameterProperty(&param, err, o, it.key(), false)) {
-        material->additionalValues[it.key()] = param;
+        // names of materials have already been parsed. Putting it in this map
+        // doesn't correctly reflext the glTF specification
+        if (it.key() != "name") material->additionalValues[it.key()] = param;
       }
     }
   }