Print dammaku's url in json output

src/you_get/extractors/bilibili.py

@@ -95,6 +95,7 @@ class Bilibili(VideoExtractor):
             qlt = self.fmt2qlt.get(quality)
             api_xml = self.api_req(cid, qlt, bangumi)
             self.parse_bili_xml(api_xml)
+            self.danmaku_url = 'http://comment.bilibili.com/{}.xml'.format(cid)
             self.danmuku = get_danmuku_xml(cid)
         else:
             for qlt in range(4, 0, -1):

src/you_get/json_output.py

@@ -16,6 +16,11 @@ def output(video_extractor, pretty_print=True):
             out['audiolang'] = ve.audiolang
     except AttributeError:
         pass
+    try:
+        if ve.danmaku_url:
+            out['danmaku_url'] = ve.danmaku_url
+    except AttributeError:
+        pass
     if pretty_print:
         print(json.dumps(out, indent=4, sort_keys=True, ensure_ascii=False))
     else: