MDL-38731 course: split course group settings header

Allow translators to translate the heading differently.

AMOS BEGIN
  CPY [groups,group],[groupsettingsheader,group]
AMOS END

course/edit_form.php

@@ -248,7 +248,7 @@ class course_edit_form extends moodleform {
         enrol_course_edit_form($mform, $course, $context);
 
 //--------------------------------------------------------------------------------
-        $mform->addElement('header','groups', get_string('groups', 'group'));
+        $mform->addElement('header','groups', get_string('groupsettingsheader', 'group'));
 
         $choices = array();
         $choices[NOGROUPS] = get_string('groupsnone', 'group');

lang/en/group.php

@@ -111,6 +111,7 @@ $string['groupnameexists'] = 'The group name \'{$a}\' already exists in this cou
 $string['groupnotamember'] = 'Sorry, you are not a member of that group';
 $string['groups'] = 'Groups';
 $string['groupscount'] = 'Groups ({$a})';
+$string['groupsettingsheader'] = 'Groups';
 $string['groupsgroupings'] = 'Groups & groupings';
 $string['groupsinselectedgrouping'] = 'Groups in:';
 $string['groupsnone'] = 'No groups';