MDL-34704 couse, accesslib: improve $CFG->courselistshortnames

1. get_context_name should respect the $CFG->courselistshortnames
setting.

2. When $CFG->courselistshortnames is on, what to display should use a
language string, rather than string concatenation. This makes it
possible for people to configure the display. For example, they might
want 'My first course [M101]' instead of 'M101 My first course'.

lib/accesslib.php

@@ -6319,7 +6319,7 @@ class context_course extends context {
                 if ($short){
                     $name .= format_string($course->shortname, true, array('context' => $this));
                 } else {
-                    $name .= format_string($course->fullname);
+                    $name .= format_string(get_course_display_name_for_list($course));
                }
             }
         }