Make Recentchanges be able to return all revisions

Recentchanges() is supposed to be able to return all revisions.
This patch therefore adds a parameter to return all revisions.
The default value for this parameter, however, is to return distinct
pages, in order to keep backward-compatibility.

Bug: 55152
Change-Id: I958be12e1a197a00e197f0746c7ee47960fb952e