* Made Special:RevisionDelete use the local variables stored in the RequestContext...

* Made Special:RevisionDelete use the local variables stored in the RequestContext object instead of global ones and removed the $skin member
* Also updated classes in includes/revisiondelete that were using the $skin member of Special:RevisionDelete
* Handle action=revisiondelete (or rather action=historysubmit&revisiondelete=1) with an Action object that sets the RequestContext object of the SpecialPage object, and in this case get the target Title object through the context instead of $wgTitle