[Request] Use Wayback Machine API to provide URLs for dead links

[Ben Ramsey]

It would be nice to use the Wayback Machine API to automatically detect whether the Internet Archive has a copy of the URL and, if so, provide a link to it.

Details are available here: https://archive.org/help/wayback_api.php

Additionally, when saving a bookmark, Pinboard could make a request to `https://web.archive.org/save/{full URL of bookmark}` to save the page in the Wayback Machine for future use.

Cheers,

Ben