web commit by EthanGlasserCamp: This is what I wanted.

doc/patchqueue/index.html_allowed.mdwn

@@ -0,0 +1,62 @@
+Instead of having files foo.html "in front of" foo/, I prefer to have foo/index.html. This patch allows that. Specifically, foo/index.type is translated to $links{'foo/'}, and bestlink looks for either "foo" or "foo/" when linking to pages. There are other miscellaneous changes that go with that -- parentlinks for "foo/" are the same as for "foo", except one directory higher; basename of "foo/" is "foo"; links to "foo/" are translated to "foo/index.html" rather than "foo/.html". (Links to "foo/" might be preferred, but that causes an infinite loop in writefile, because apparently dirname("foo/") == "foo/" on my system for reasons that aren't clear to me.)
+
+    Index: IkiWiki/Render.pm
+    ===================================================================
+    --- IkiWiki/Render.pm       (revision 1497)
+    +++ IkiWiki/Render.pm       (working copy)
+    @@ -40,6 +40,10 @@
+        my $path="";
+        my $skip=1;
+        return if $page eq 'index'; # toplevel
+    +   if ($page =~ m{/$}){
+    +           $page =~s{/$}{};
+    +           $path="..";
+    +   }
+        foreach my $dir (reverse split("/", $page)) {
+                if (! $skip) {
+                        $path.="../";
+    Index: IkiWiki.pm
+    ===================================================================
+    --- IkiWiki.pm      (revision 1497)
+    +++ IkiWiki.pm      (working copy)
+    @@ -170,6 +170,7 @@
+     sub basename ($) { #{{{
+        my $file=shift;
+
+    +   $file=~s!/$!!;
+        $file=~s!.*/+!!;
+        return $file;
+     } #}}}
+    @@ -196,12 +197,14 @@
+        my $type=pagetype($file);
+        my $page=$file;
+        $page=~s/\Q.$type\E*$// if defined $type;
+    +   $page=~s#index$## if $page=~m{/index$};
+        return $page;
+     } #}}}
+
+     sub htmlpage ($) { #{{{
+        my $page=shift;
+
+    +   return $page."index.html" if $page=~m{/$};
+        return $page.".html";
+     } #}}}
+
+    @@ -264,6 +267,7 @@
+        my $page=shift;
+        my $link=shift;
+
+    +   $page =~ s!/$!!;
+        my $cwd=$page;
+        do {
+                my $l=$cwd;
+    @@ -273,6 +277,9 @@
+                if (exists $links{$l}) {
+                        return $l;
+                }
+    +           if (exists $links{$l.'/'}){
+    +                   return $l.'/';
+    +           }
+                elsif (exists $pagecase{lc $l}) {
+                        return $pagecase{lc $l};
+                }