As of version 2.0, ikiwiki will switch to enabling the 'usedirs' setting by
default. This *will* break all URLs to wikis that did not have 'usedirs'
turned on before. You can either follow this procedure to convert your wiki
to usedirs, or edit your setup file and turn usedirs back off.

* Upgrade ikiwiki to 2.0.
* Force ikiwiki to rebuild your wiki, by using `ikiwiki-mass-rebuild`,
  or manually.
* Since usedirs is enabled, ikiwiki will have created a bunch of new
  html files. Where before ikiwiki generated a `dest/foo.html`, now it will
  generate `dest/foo/index.html`. The old html files will be removed.
* If you have a blog that is aggregated on a Planet or similar, all the
  items in the RSS or atom feed will seem like new posts, since their URLs
  have changed. See [[howto_avoid_flooding_aggregators]] for a workaround.
* Now all the URLs to pages in your wiki have changed. See
  [[redirections_for_usedirs]] for instructions on setting up redirections
  to keep the old URLs working.

Why usedirs?
------------
There are several advantages to `usedirs`, including simpler URLs, URLs that
aren't dependent on the underlying implementation (`.html`), and being able to
use URLs as tags as described in the [rel-tag
microformat](http://microformats.org/wiki/rel-tag).

The main disadvantage is that it is harder to browse using `file://` URIs,
since `file:///dir/` doesn't automatically translate to `dir/index.html`. This
is something one could fix in the browser though.
