Allows you to display a QR code linking to a geocache or trackable listing on Geocaching.com

To see the QR code on a cache listing, click on the triangle to the right of the GC-code at the top-right of the page. Trackables should work in a similar way. As of v1.2.0, also adds a link to show a QR code to the cache details popup on the main Geocaching Maps page.