New comment fetch

[Reeywhaar]

It's 2k19, and I think it will be good if remark have option to fetch new comments, just like in chat, where you don't have to reload a page to see new comment. Github also shows new comments immediately after it was posted.

So, idea from the design view looks like this:

Notice thread margin on the left, and "2 new comments" button on the right, which upon click shows comments which appeared after user loaded the page.

From the backend/frontend side its:

• server option autorefresh or with values off(default)|socket or something.
• make use of https://github.com/googollee/go-socket.io which is basically websockets on steroids with option to downcast to http long polling and other features.
• off value can be used to turn off autorefresh, as lot of websocket connections can kill cheap server.
• on the frontend still https://socket.io/ may be used

Just my 2¢

[umputun]

I have added /stream/info API allowing to subscribe to update events. See #336 for details

note: this is not "comment fetch" but a way to get info if new comments were added (or removed) from the thread. This is not websocket either but a long connection with a timeout.

[Reeywhaar]

Hope I'll get the time this weekend

[umputun]

Do you think we need a way to control stream/no-stream from my side? For example, we can have this streaming optional globally and populate "streams": true/false as a part of /config response.