Git merges in Moodle 3.1.16 by Andrew Nicols

commit be5d94c45445f951bf7cb2910c76bbd26acbc1fc
Author: Andrew Nicols <andrew@nicols.co.uk>
Date:   Tue, 08 Jan 2019 06:57:07 +0800
Tag:    v3.1.16

Merge branch 'MDL-63276_31' of https://github.com/stronk7/moodle into MOODLE_31_STABLE