[youtube:comments] Move comment extraction to new API (#466)

Closes #438, #481, #485 

Authored by: colethedj

README.md

@@ -1335,7 +1335,10 @@ # EXTRACTOR ARGUMENTS
     * `skip`: `hls` or `dash` (or both) to skip download of the respective manifests
     * `player_client`: `web` (default) or `android` (force use the android client fallbacks for video extraction)
     * `player_skip`: `configs` - skip requests if applicable for client configs and use defaults
-
+    * `comment_sort`: `top` or `new` (default) - choose comment sorting mode (on YouTube's side).
+    * `max_comments`: maximum amount of comments to download (default all).
+    * `max_comment_depth`: maximum depth for nested comments. YouTube supports depths 1 or 2 (default). 
+    
 * **funimation**
     * `language`: Languages to extract. Eg: `funimation:language=english,japanese`
     * `version`: The video version to extract - `uncut` or `simulcast`