Directory:  install/SiteUpgrades

Files containing PHP upgrade code to be run after the application framework
has been intialized can be placed in this directory.  PHP code that must
be run before the application framework has been initialized should go into
install/DBUpgrades.

Code must be idempotent (no additional effect if run multiple times).

Any error messages should be returned by putting them in an array in
$GLOBALS["G_ErrMsgs"].

Upgrade files should be named "SiteUpgrade--VERSION.php", where VERSION is
the version being upgraded to.
