Want to turn on the `usedirs` setting on an existing wiki without breaking
all the links into it? Here's a way to do it for Apache, using the
RewriteEngine. This example is for a wiki at the top of a web site, but can
be adapted to other situations.

	# pages
	RewriteCond $1 !^/~          # these pages
	RewriteCond $1 !^/doc/       # are not part of
	RewriteCond $1 !^/ajaxterm   # the wiki, so
	RewriteCond $1 !^/cgi-bin/   # don't rewrite them
	RewriteCond $1 !.*/index$
	RewriteRule (.+).html$ $1/ [R]
	
	# rss feeds
	RewriteCond $1 !^/~
	RewriteCond $1 !.*/index$
	RewriteRule (.+).rss$ $1/index.rss
	
	# atom feeds
	RewriteCond $1 !^/~
	RewriteCond $1 !.*/index$
	RewriteRule (.+).atom$ $1/index.atom