FEATURE: Inline (Mini) Oneboxing

see:
https://meta.discourse.org/t/mini-inline-onebox-support-rfc/66400?source_topic_id=66066

lib/pretty_text/shims.js

@@ -49,6 +49,10 @@ function __getURL(url) {
   return url;
 }
 
+function __lookupInlineOnebox(url) {
+  return __helpers.lookup_inline_onebox(url);
+}
+
 function __getTopicInfo(i) {
   return __helpers.get_topic_info(i);
 }