MDL-45229 event: Validate sectionnum in course_section_updated
MDL-45229 event: Trigger event when section visibility changes
MDL-45221 admin: configexecutable admin settings should only accept files
Merge branch 'MDL-45229-master' of git://github.com/FMCorz/moodle
MDL-45312 qtype_missingtype or qbehaviour_missing cannot be uninstalled.

They are required by the system.
Merge branch 'MDL-45221-master' of git://github.com/andrewnicols/moodle
Merge branch 'MDL-45312' of git://github.com/timhunt/moodle