MDL-47562 gradereport_singleview: New lang string for save button

AMOS BEGIN
    CPY [save,admin],[save,gradereport_singleview]
AMOS END

grade/report/singleview/classes/local/screen/tablelike.php

@@ -226,7 +226,7 @@ abstract class tablelike extends screen {
     public function buttons() {
         $save = html_writer::empty_tag('input', array(
             'type' => 'submit',
-            'value' => get_string('update'),
+            'value' => get_string('save', 'gradereport_singleview'),
         ));
 
         return array($save);

grade/report/singleview/lang/en/gradereport_singleview.php

@@ -51,6 +51,7 @@ $string['overridefor'] = 'Override for {$a}';
 $string['overridenone'] = 'Do not override any grades';
 $string['pluginname'] = 'Single view';
 $string['savegrades'] = 'Saving grades';
+$string['save'] = 'Save';
 $string['savegradessuccess'] = 'Grades were set for {$a} items';
 $string['selectgrade'] = 'Select grade item...';
 $string['selectuser'] = 'Select user...';