Add support for Wayback machine

[kristofa]

The idea to support Wayback machine came up in the Pinboard user group:

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.

[shazron]

Which is the Memento API, which https://archive.today supports as well:

An advantage of using Archive.today over WayBack Machine is that it can support sites that rely heavily on Javascript, visuals, and even social media applications like Twitter. This is a huge benefit to using this platform as it allows users to have all of the information they want on almost any website they want. Another benefit of this platform is that is stores two copies of each page: one static one, and one that contains the pages links. Unlike the WayBack Machine, Archive.today does not use robots.txt files which have lead to a loss of data in the past [1]

[1] https://digitaltrawler.com/10-wayback-machine-alternatives/