Author: Tony Butler
MDL-62225 assignfeedback_editpdf: Add alt text for nav button shortcuts
http://git.moodle.org/gw?p=moodle.git;a=commit;h=8e642421313ca2f7234a8d47e49a4b8cfbd84530
http://github.com/moodle/moodle/commit/8e642421313ca2f7234a8d47e49a4b8cfbd84530
+ 3.6 en [navigatenext,assignfeedback_editpdf]
+ 3.6 en [navigateprevious,assignfeedback_editpdf]