Steem discovery feed.

[toniwidmo]

Based on the work of steemian littlejoeward, with permission.

Could probably do this client side using local storage object: https://www.w3schools.com/html/html5_webstorage.asp

1. First time user selects this on a given browser, it will need to create a list of 'curators', which is to say users that vote on the same things, and rank them by number of votes in common, and store this list in local storage. Also store when it was last run, so we know when we need to refresh. This is basically step 4, which will normally run in the background.

2. Import list of posts voted on by highest curator that hasn't been imported in the past three days, no older that 6 days. Store post ids. Update the last imported date for this user. If not enough posts, also import next user until minimum post count is reached.

3. Display and order posts by score.

4. Daily update. This can be run in background, no more that once in a 24 hour period, whilst user looks at existing posts. Once update is complete, a message can invite user to update display. This will get users votes from past seven days. It will remove unread posts older than 6 days. Votes are processed to get other users that made same votes and update their scores. Votes for anything in the discovery feed will remove it from the feed. Updates scores of remaining posts in discovery feed based on other voters.

5. Each post should get a 'Mark read' button that will remove it from feed. Also, a 'mark read to here' button should remove all prior posts as well. Removing posts should also move them to list of read posts in local data.