A simple context-menu plugin to facilitate opening an arbitrary resource as
plain text (text/plain).

You want to read a file online. It might be source code. It might not. Who
cares? The point is you know it's a plain text file and you want to view it
in the browser - NOW!

Known Issues:
Doesn't set the URL property of the new page.
Doesn't allow "View-Source" on the new page, although this is a bit
redundant.
Technically the new page is still mimetype: text/html.