Completely remove names_dicts from the diff parser.

test/test_parser/test_old_fast_parser.py

@@ -27,7 +27,7 @@ def test_carriage_return_splitting():
         '''))
     source = source.replace('\n', '\r\n')
     p = FastParser(load_grammar(), source)
-    assert [n.value for lst in p.module.names_dict.values() for n in lst] == ['Foo']
+    assert [n.value for lst in p.module.used_names.values() for n in lst] == ['Foo']
 
 
 def test_class_in_docstr():