Removed unused globals $wgHooks, $wgBlockAllowsUTEdit, $wgUser, $wgOut
$wgUser was already set global at function beginning.
Moved global out of switch
* Adds a condition fa_deleted=0 if the user does not have the suppressrevision rights. This field is unindexed. This should however not be a big problem as files with fa_deleted are rare. Unfortunately this hides files that do not have DELETED_RESTRICTED, but I don't know how bad fa_deleted & DELETED_RESTRICTED = 0 is for performance
* Added deletedfile, deletedcomment, deleteduser and deletedrestricted to the output for what I think are appropriate fa_deleted fields, but it's hard to tell what's corrent without a single line of documentation or even comment in the code. Perhaps somebody can dig up a commit message where the purpose of the constants is explained?
* Introduced a "cache mode" concept to simplify the header generation code, and to avoid odd results when conflicting cache header requests are received from submodules, or at least to formalise the handling of such cases.
* Made the cache mode private by default, so that code written in ignorance of caching tends to be safe. If different query modules are used in a single request, private caching is preferred over public caching.
* Removed the "must-revalidate" option from all CC headers, this is really specific to page views with a hacked squid in front, I don't think it's applicable here.
* Made the watchlist module private. This is really the definition of private data. There's nothing in the HTTP spec that says the URL for a CC:public request is private and can't be leaked. CC:private provides protection against unknown proxy behaviour.
* In ApiQueryAllmessages: avoid calling $wgLang->getCode() to check if it's necessary to make a new $wgLang when lang= is specified, since this is the only thing that unstubs $wgUser.
* Removed "FIXME: should this check $user instead of $wgUser?" Answer is no.
