Database.php:

Database.php:
* Proper handling of LIST_OR in makeList()
LinkBatch.php:
* Added isEmpty() and getSize() functions.
Query.php:
* Implemented double-redirects query (disabled until caching is done)
* Implemented backlinks query.
* Rewrote page info generator to allow both titles and pageIds to be specified.
* Security check for read-access.
* Output filtering prevents exposure of the internal data.
* Added transactional consistency (not sure its needed here)