CONTRIB-4787 :: email non-respondents in an anonymous questionnaire

Signed-off-by: Joseph Rézeau <moodle@rezeau.org>
Fixed bug in questionnaire_get_survey_select function.

Signed-off-by: Joseph Rézeau <moodle@rezeau.org>
Fixed bug in qsettings when no feedback sections.

Signed-off-by: Joseph Rézeau <moodle@rezeau.org>
Fixed small bug in qsettings.php

Signed-off-by: Joseph Rézeau <moodle@rezeau.org>
CONTRIB-4800 :: Enable teachers to preview template or public questionnaires located in courses where they are not enrolled

Signed-off-by: Joseph Rézeau <moodle@rezeau.org>