MDL-38241 qtype_match: should say Blanks for 3 more questions.

Currently it says Blanks for 3 more choices, like multichoice, which is
confusing.

AMOS BEGIN
 MOV [addmoreqblanks,qtype_match],[blanksforxmorequestions,qtype_match]
AMOS END

question/type/match/edit_match_form.php

@@ -70,6 +70,13 @@ protected function definition_inner($mform) {
         $this->add_interactive_settings(true, true);
     }
 
+    /**
+     * Language string to use for 'Add {no} more {whatever we call answers}'.
+     */
+    protected function get_more_choices_string() {
+        return get_string('blanksforxmorequestions', 'qtype_match');
+    }
+
     protected function data_preprocessing($question) {
         $question = parent::data_preprocessing($question);
         $question = $this->data_preprocessing_combined_feedback($question, true);

question/type/match/lang/en/qtype_match.php

@@ -22,9 +22,9 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
-$string['addmoreqblanks'] = '{no} More Sets of Blanks';
 $string['answer'] = 'Answer {$a}';
 $string['availablechoices'] = 'Available choices';
+$string['blanksforxmorequestions'] = 'Blanks for {no} more questions';
 $string['correctansweris'] = 'The correct answer is: {$a}';
 $string['filloutthreeqsandtwoas'] = 'You must provide at least two questions and three answers. You can provide extra wrong answers by giving an answer with a blank question. Entries where both the question and the answer are blank will be ignored.';
 $string['nomatchinganswer'] = 'You must specify an answer matching the question \'{$a}\'.';