Git merges in Moodle 1.9.13 by Andrew Davis (andyjdavis)

commit d221a3839d2858e7c5243511dbce0375fead5856
Author: Andrew Davis (andyjdavis) <andrew@moodle.com>
Date:   Tue, 10 May 2011 11:17:45 +0800
Tag:    v1.9.13

Merge branch 'MOODLE_19_STABLE' of git://git.moodle.org/moodle into MOODLE_19_STABLE