fix string id support to also include in_reply_to_... fields

mastodon/Mastodon.py

@@ -1084,10 +1084,11 @@ class Mastodon:
         """
         Converts json string IDs to native python bignums.
         """
-        if ('id' in json_object and
+        for key in ('id', 'in_reply_to_id', 'in_reply_to_account_id'):
-                isinstance(json_object['id'], six.text_type)):
+            if (key in json_object and
+                    isinstance(json_object[key], six.text_type)):
                 try:
-                json_object['id'] = int(json_object['id'])
+                    json_object[key] = int(json_object[key])
                 except ValueError:
                     pass