Info stream (#336)

* add /stream/info as a cheap way to subscribe to comment updates #253

* add check for lastTS change to allow proper info streams in no-cache mode

* check write error in info stream and terminate

* flaky info stream test

* add stream info to readme

* separate timeout middleware foe each route's group

* debug info on stream close

* fix test for streams

* stream timeout on inactivity only

* throttle streams to 500

* restore common throttle

README.md

@@ -624,7 +624,8 @@ Sort can be `time`, `active` or `score`. Supported sort order with prefix -/+, i
   }
   ```
 
-* `GET /api/v1/info?site=site-idd&url=post-ur` - returns `PostInfo` for site and url
+* `GET /api/v1/info?site=site-idd&url=post-url` - returns `PostInfo` for site and url
+* `GET /api/v1/stream/info?site=site-idd&url=post-url` - returns stream with `PostInfo` records ("\n" separated) for site and url`
 
 ### RSS feeds