Added an extra sort option for 'gilded'

Implemented 'gilded' sort both in the banner bar (by pushing the '6' key), and in the prompt (by entering '/subreddit/gilded')

rtv/subreddit_page.py

@@ -66,6 +66,7 @@ class SubredditPage(Page):
         else:
             self.refresh_content(order='hot')
 
+
     @SubredditController.register(Command('SORT_TOP'))
     def sort_content_top(self):
         order = self._prompt_period('top')
@@ -85,6 +86,17 @@ class SubredditPage(Page):
         else:
             self.refresh_content(order='rising')
 
+    @SubredditController.register(Command('SORT_GILDED'))
+    def sort_content_gilded(self):
+        if self.content.query:
+            order = self._prompt_period('comments')
+            if order is None:
+                self.term.show_notification('Invalid option')
+            else:
+                self.refresh_content(order=order)
+        else:
+            self.refresh_content(order='gilded')
+
     @SubredditController.register(Command('SORT_NEW'))
     def sort_content_new(self):
         self.refresh_content(order='new')