This makes them more efficient. It also fixes a longstanding bug,
where if only a small set of pages were considered by orphans/pagestats,
changes to links on other pages failed to cause an update.
+ * linkmap: Use a combination of presence and link dependencies.
+ This makes the map be regenerated much less frequently in many cases,
+ so larger maps are more practical to use now.
* Transitive dependencies are now correctly supported.
* Rebuild wikis on upgrade to this version to get improved dependency
info.