Delete records from {masquarade_users} after user delete

Now there is garbage left in {masquarade_users} if one of users with uid uid_from or user_to deleted. You should add the following code to masquerade_user.

    case 'delete':
      db_query("DELETE FROM {masquerade_users} WHERE uid_from = %d OR uid_to = %d", $edit_user->uid, $edit_user->uid);
      break;