N°3663 Group exception classes in /application/exceptions

Original files kept for compatibility issues :
- core/coreexception.class.inc.php

There are remaining exceptions in /core/oql, but those files are generated

application/exceptions/mysql/MySQLHasGoneAwayException.php

@@ -0,0 +1,32 @@
+<?php
+/*
+ * @copyright   Copyright (C) 2010-2021 Combodo SARL
+ * @license     http://opensource.org/licenses/AGPL-3.0
+ */
+
+/**
+ * Class MySQLHasGoneAwayException
+ *
+ * @see https://dev.mysql.com/doc/refman/5.7/en/gone-away.html
+ * @since 2.5.0 N°1195
+ */
+class MySQLHasGoneAwayException extends MySQLException
+{
+	/**
+	 * can not be a constant before PHP 5.6 (http://php.net/manual/fr/language.oop5.constants.php)
+	 *
+	 * @return int[]
+	 */
+	public static function getErrorCodes()
+	{
+		return array(
+			2006,
+			2013,
+		);
+	}
+
+	public function __construct($sIssue, $aContext)
+	{
+		parent::__construct($sIssue, $aContext, null);
+	}
+}