Addressbook - limit previous / next event to the previous / next 2 years, instead of all time

Gives slightly faster performace and reduces memory useage.

api/src/Contacts.php

@@ -1611,6 +1611,8 @@ class Contacts extends Contacts\Storage
 
 		$bocal = new calendar_bo();
 		$events = $bocal->search(array(
+			'start' => strtotime('2 years ago'),
+			'end'	=> strtotime('2 years from now'),
 			'users' => $uids,
 			'enum_recuring' => true,
 		));