* (bug 22918) Feed cache keys now use $wgRenderHashAppend (so that it doesn't mix...

* (bug 22918) Feed cache keys now use $wgRenderHashAppend (so that it doesn't mix between secure.wikimedia.org and normal sites)
* Modified the timestamp key to use all parameters, otherwise various entries are sharing the same timestamp key and thus some of them can be served even though they are out of date. Consider the following case:
** Two requests for feeds sharing the same timestamp key are done
** Someone edits a page (or whatever else that change the recentchanges table)
** A user request one of the two feed above, the feed is correctly re-generated and the timestamp key changed
** A request for the other feed is done, this time the timestamp is the one of the request just above and the cached version will be served (even though it should not)

Based on a patch by Bawolff.