* Introducing bit field for database parameters

* Introducing bit field for database parameters
** Database constructor calling sequence, and Database::newFromParams()
** Including flags in the server initialisation structs
** Support for setting appropriate flags from legacy globals in Setup.php
** Moved some defines to Define.php so that they can be used in LocalSettings.php, most importantly the bit field constants

* Changes related to post-parse link colouring
** Turn the link cache back on when using it for updating the links table
** No longer need to call preFill() on page view

* Better synchronisation of slave servers
** Rearranged getConnection()
** System for beginning and committing transactions when multiple connections are open
** wfAbruptExit() commits transactions, wfErrorExit() does not. Various functions changed to use wfErrorAbort()

* Allowed reporting of database errors during deferred updates by moving them above output()