Removes Join interface, add referer headers while crawling, adds touch calls in updateDictionary to prevent crawl stopping, a-chris

<?php
/**
 * SeekQuarry/Yioop --
 * Open Source Pure PHP Search Engine, Crawler, and Indexer
 *
 * Copyright (C) 2009 - 2020  Chris Pollett chris@pollett.org
 *
 * LICENSE:
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 * END LICENSE
 *
 * @author Chris Pollett chris@pollett.org
 * @license https://www.gnu.org/licenses/ GPL3
 * @link https://www.seekquarry.com/
 * @copyright 2009 - 2020
 * @filesource
 */
namespace seekquarry\yioop\library;

/**
 * Marker interface used to say that a class has supports a join()
 * callback method. IndexArchiveBundle has methods which take objects
 * that implement Join. For activities which may take a long time
 * such as index saving index tier merging IndexArchiveBundle will
 * periodically call the Join objects join method so that it can continue
 * processing rather than blocking entirely until the long running method
 * completes
 *
 * @author Chris Pollett
 * @see WebQueueBundle
 */
interface Join
{
    /**
     * A callback function which will be invoked periodically by a method
     * of another object that runs a long time.
     */
    public function join();
}