Scrutinizer Auto-Fixes

This patch was automatically generated as part of the following inspection:
https://scrutinizer-ci.com/g/timw4mail/Query/inspections/89ed2aa4-7aae-45bb-9289-ebb27a60ef13

Enabled analysis tools:
 - PHP Analyzer
 - PHP Copy/Paste Detector
 - PHP PDepend

classes/db_pdo.php

@@ -82,7 +82,7 @@ abstract class DB_PDO extends PDO {
 	 *
 	 * @param string $sql
 	 * @param array $data
-	 * @return mixed PDOStatement / FALSE
+	 * @return PDOStatement PDOStatement / FALSE
 	 * @throws InvalidArgumentException
 	 */
 	public function prepare_query($sql, $data)

classes/query_builder.php

@@ -856,7 +856,7 @@ class Query_Builder implements iQuery_Builder {
 	 *
 	 * @param int $limit
 	 * @param int $offset
-	 * @return string
+	 * @return Query_Builder
 	 */
 	public function limit($limit, $offset=FALSE)
 	{

drivers/firebird/firebird_driver.php

@@ -108,7 +108,7 @@ class Firebird extends DB_PDO {
 	 * Wrapper public function to better match PDO
 	 *
 	 * @param string $sql
-	 * @return $this
+	 * @return Firebird_Result
 	 * @throws PDOException
 	 */
 	public function query($sql)
@@ -135,7 +135,7 @@ class Firebird extends DB_PDO {
 	 *
 	 * @param string $query
 	 * @param array $options
-	 * @return $this
+	 * @return Firebird_Result
 	 * @throws PDOException
 	 */
 	public function prepare($query, $options=NULL)
@@ -155,7 +155,7 @@ class Firebird extends DB_PDO {
 	/**
 	 * Start a database transaction
 	 *
-	 * @return bool
+	 * @return boolean|null
 	 */
 	public function beginTransaction()
 	{
@@ -193,7 +193,7 @@ class Firebird extends DB_PDO {
 	 *
 	 * @param string $sql
 	 * @param array $args
-	 * @return resource
+	 * @return Firebird_Result
 	 */
 	public function prepare_execute($sql, $args)
 	{

drivers/firebird/firebird_result.php

@@ -126,7 +126,7 @@ class Firebird_Result extends PDOStatement {
 	 * Run a prepared statement query
 	 *
 	 * @param  array $args
-	 * @return bool
+	 * @return Firebird_Result
 	 */
 	public function execute($args = NULL)
 	{

drivers/sqlite/sqlite_driver.php

@@ -80,7 +80,7 @@ class SQLite extends DB_PDO {
 	/**
 	 * List system tables for the current database
 	 *
-	 * @return array
+	 * @return string[]
 	 */
 	public function get_system_tables()
 	{

drivers/sqlite/sqlite_sql.php

@@ -172,7 +172,7 @@ SQL;
 	/**
 	 * SQL to show list of field types
 	 *
-	 * @return array
+	 * @return string[]
 	 */
 	public function type_list()
 	{