Closes #4: Sort calendar list alphabetically

plugins/calendar/calendar.php

@@ -405,6 +405,11 @@ class calendar extends rcube_plugin
           $this->_cal_driver_map[$id] = $driver;
         }
       }
+
+      // Sort calendars alphabetically
+      uasort($this->_cals, function($a, $b) {
+        return strcasecmp($a["listname"], $b["listname"]);
+      });
     }
 
     return $this->_cals;