Add option "hidden" to hgwebdir.

TODO: should this option be renamed to 'hide_from_index' or
maybe to 'index_ignore' (like Apache's mod_autoindex) ?

doc/hgrc.5.txt

@@ -525,6 +525,8 b' web::'
     Default is "unknown".
   errorlog;;
     Where to output the error log. Default is stderr.
+  hidden;;
+    Whether to hide the repository in the hgwebdir index. Default is false.
   ipv6;;
     Whether to use IPv6. Default is false.
   name;;

mercurial/hgweb/hgwebdir_mod.py

@@ -142,6 +142,9 b' class hgwebdir(object):'
                 def get(section, name, default=None):
                     return u.config(section, name, default, untrusted=True)
 
+                if u.configbool("web", "hidden", untrusted=True):
+                    continue
+
                 url = ('/'.join([req.env["REQUEST_URI"].split('?')[0], name])
                        .replace("//", "/")) + '/'