MDL-44670 themes: Updated screenshots of Clean and More
MDL-44590 category: correct get_string component
MDL-44590 behat: Add test for course category idnumber duplication
MDL-44804 editor_atto: JS error when filepicker is disabled
MDL-44822 assignfeedback_editpdf: Stop test generation in is_enabled()

This change also moves one of the checks in test_gs_path. If
generateimage is false, there's no need to stat for the fixture file.
MDL-44701 gradereport_grader: Display warning on navigation if unsaved grades are present
MDL-44837 Behat: 'dialogue' selector only works for confirm dialogues

The dialogue selector in Behat (used only in one place) didn't work for
other types of standard Moodle notification dialogue.
MDL-44733 add support for disabling of scheduled tasks
MDL-44754 Atto: Explaining what group names are used for in toolbars
MDL-44808 atto_table: Remove accessibility information from dialogue
Merge branch 'MDL-44804-master' of git://github.com/FMCorz/moodle
MDL-44767 atto_editor: Browser hangs when making a selection
MDL-44764 atto_image: Reword the alt related labels
MDL-44757 atto_equation: Use Moodle Docs URL for TeX doc
Merge branch 'MDL-44822' of git://github.com/aolley/moodle
MDL-44583 Assign: performance fixes
MDL-44733 add disabled class rows with disabled scheduled tasks
Merge branch 'MDL-44764-master' of git://github.com/FMCorz/moodle
Merge branch 'MDL-44808-master' of git://github.com/FMCorz/moodle
Merge branch 'w14_MDL-44733_m27_taskdisabled' of git://github.com/skodak/moodle