MDL-36009 grader_gradereport: table fixes, hiding icons from screen readers
MDL-44657 forms: Form identifiers should only contain basic characters
MDL-47590 question backup: include response file only with userdata
Merge branch 'MDL-36009-27' of git://github.com/jethac/moodle into MOODLE_27_STABLE
Merge branch 'MDL-44657-27' of git://github.com/FMCorz/moodle into MOODLE_27_STABLE
Merge branch 'MDL-47590_27' of git://github.com/timhunt/moodle into MOODLE_27_STABLE