Track changes

[xamgore]

Sometimes people post news and change them in time (like, 1 hour, 1 day). It is important to update instant view previews too.

Grab RSS feed, go through items:

• if the item is new:
  1. send link to telegram
  2. save messages' ids
  3. save text of the item's text
• if the item is old:
  1. compute hash
  2. check with stored hash
     • if same: do nothing
     • else: update telegram messages and resave hash

Links must have the following format:

https://mmcs.sfedu.ru/...?rhash=...&h={item text hash}