wish: support for "search engines"

[markstos]

In Firefox, a "custom search engine" is implemented as a bookmark with a "keyword" defined, and a "%s" in the bookmark. Chromium seems to store search engines definitions elsewhere (but I'm not certain where yet). When exporting bookmarks, it would be nice to find and include these as well, since Firefox and (presumably) other browsers will recognize them as bookmarks.

( I recently developed sciatica, and py-chrome-bookmarks has helped me to set up a more comfortable environment at home by allowing me to access my bookmarks from work. Thanks! )