Updated FSF's address
mallard/html: Be robust against multiple desc elements

Future Mallard versions may allow multiple descs with role
attributes, just like info titles.
Remove the code watermark image

It wasn't being used by yelp or yelp-tools anyway.
db2html-inline: Use kdb to fix DocBook keycap styling

I broke this by accident a while ago when I changed Mallard
to use the kdb element for key elements.

https://bugzilla.gnome.org/show_bug.cgi?id=709943
Version 3.11.5
mal2html-links: Added "norwich" links style for new index splash design
mal2html-page: Support "hidden" style hint on page/section titles