Include chart(s) for personal stats page

[jeroenheijmans]

On the https://adventofcode.com/2018/leaderboard/self page (and those for other years) we could also show some fun stats. Something based off this codepen perhaps?

The codepen only does something with rank for star 2, but other cool stuff would include:

• difference between two ranks
• difference in time to star 1 and star 2
• score (though for most people that's just 0 :D)

Of course the extension would only be able to see the html page of 1 year at a time (but I guess we can hack our way around it by 'saving' the scraped data for later, when the user switches years?).

[jeroenheijmans]

Tagging this 'hacktoberfest' although note that this is not really a small thing to add. Still welcome if someone wants to give it a shot.

[jeroenheijmans]

PS. There's a advent-of-code-charts channel in the contributing.today Discord where I'll be if anyone has hacktoberfest-related questions!

[jeroenheijmans]

I'm eyeballing this for a 2023 update, but only if there will be a 2023 AoC edition at all 😅... so letting this sit until at least fall, might pick it up after that.

[jeroenheijmans]

There is a 2023 edition! However, all the updates from Jan/Feb and from this Nov focused on other features. Perhaps in 2024 the Personal Leaderboards will get some love.

PS. Note that there was some inspiration on Reddit too for personal leaderboards improvements.