Git commits in Moodle 3.5.7 by Paul Holden

commit 4cf939c6389bedf341af890832fe0a94d0f1704e
Author: Paul Holden <pholden@greenhead.ac.uk>
Date:   Wed, 27 Mar 2019 20:56:16 +0800
Tag:    v3.5.7

MDL-64511 privacy: encode data URL when loading content.