favicon: Revert to the original transparent background. I had originally flattened the image with the out-dated expectation that we couldn't do a favicon with alpha in it. I was glad to find I was wrong on that point.
Add an actual mail-related favicon. This replaces the default ikiwiki favicon. Thanks to "Sebastian Spaeth" <Sebastian@SSpaeth.de> for the public-domain artwork with the original SVG available here: http://github.com/spaetz/notmuch-all-feature/tree/master/contrib/
Copy in all content from the default basewiki It seems much more straightforward to me to just edit actual files rather than depending on some mystic files outside of revision control.