Added preliminary db drivers and ant task to update database calls to use drivers.
Added some more funcs to fix deprecated mysql task.  This is the version that was run on Xataface.
Fixed deprecated preg_replace e
Changed all mysql_ function calls to use the xf_db_ wrapper functions.  Added driver convention in xf/db/drivers .  So far there are drivers for mysql and mysqli only.  Not heavily tested yet either but seem to work on preliminary sample apps.  Driver can be specified by adding driver attribute to the _database section of the conf.ini file.  E.g. driver=mysql or driver=mysqli, where the driver name corresponds to the name of the PHP file in xf/db/drivers.
Removed PEAR.php accidentally added in last commit
Secured installer so that it is disabled by default.  You now have to rename the installer.disabled file to installer.enabled in order for the installer to work.
Added .htaccess file to cut off access to everything in Xataface directory except for images, javascripts, and stylesheets.
Removed redundant blob.php file.