Make it possible to directly run sub-libs (feeds, crawler, readabilite)

Run `python -im morss.feeds http://website.sample/rss.xml` and so on

morss/feeds.py

@@ -754,3 +754,10 @@ class ItemJSON(Item, ParserJSON):
                 return
 
             cur = cur[node]
+
+
+if __name__ == '__main__':
+    from . import crawler
+
+    data, con, contenttype, encoding = crawler.adv_get(sys.argv[1] if len(sys.argv) > 1 else 'https://www.nytimes.com/', follow='rss')
+    feed = parse(data, url=con.geturl(), mimetype=contenttype, encoding=encoding)