xkcd x2 per IcyLandMantle

This add-on adds to the line of buttons above and below the comic image on xkcd pages. The new button (marked "x 2") provides a link to the double-sized version of the comic that is provided for most editions.

The comic URL is scraped from the page, so if a larger version is not available for a specific comic, the button may not appear.

Note before reporting problems: If the button doesn't appear (or doesn't work) for specific comics only, there is probably nothing I can do.

Some code was based on the MIT-licensed "explain xkcd" extension: https://cup.aihedy.com/en-GB/firefox/addon/xkcd-explainer/. xkcd x2 is designed to work correctly with this extension.