On Hover Footnote Preview

[shravanngoswamii]

Added On-Hover Footnote Preview feature! I used a small jQuery script for fetching the footnote definitions from the end of the page and its working very fine!

closes #2080

[fredrikekre]

Nice. This would be awesome to have for docstring references too, but might be a bit more tricky since it doesn't have to be on the same page.

[shravanngoswamii]

Nice. This would be awesome to have for docstring references too, but might be a bit more tricky since it doesn't have to be on the same page.

I can look into that if you can just tell me the part of codebase which deals with it!

[mortenpi]

Very cool! It looks like you can run into some "layout" issues when you have small windows or are close to edges I guess:

I don't know if there are any easy ways to work around this or not. We can always iterate on it later as well, if there aren't.

A few other thoughts:

• We could use data-* attributes to label the footnote content, to make it reusable maybe?
• I'm pretty happy to have JS copy the HTML/DOM around (as opposed to generating it with Julia). Although if we do want stuff from other pages, then we might indeed have to generate those as hidden elements.

Generally, I think I'd be happy to merge this pretty much as is, and iterate in follow-up PRs. Or if you want to fiddle with it a bit more, we can also wait.

[shravanngoswamii]

I would be happy if you can wait a little! Sorry, actually I did not test it on small windows! I will make some changes in it as soon as I get some time!