[DBAL-243] Remove Connection#setCharset()

UPGRADE

 # Upgrade to 2.3
 
+## Doctrine\DBAL\Connection#setCharsetSQL() removed
+
+This method only worked on MySQL and it is considered unsafe on MySQL to use SET NAMES UTF-8 instead
+of setting the charset directly on connection already. Replace this behavior with the
+connection charset option:
+
+Before:
+
+    $conn = DriverManager::getConnection(array(..));
+    $conn->setCharset('UTF8');
+
+After:
+
+    $conn = DriverManager::getConnection(array('charset' => 'UTF8', ..));
+
 ## Doctrine\DBAL\Schema\Table#renameColumn() removed
 
 Doctrine\DBAL\Schema\Table#renameColumn() was removed, because it drops and recreates

lib/Doctrine/DBAL/Connection.php

@@ -539,16 +539,6 @@ class Connection implements DriverConnection
         return $this->executeUpdate($query, array_values($data), $types);
     }
 
-    /**
-     * Sets the given charset on the current connection.
-     *
-     * @param string $charset The charset to set.
-     */
-    public function setCharset($charset)
-    {
-        $this->executeUpdate($this->_platform->getSetCharsetSQL($charset));
-    }
-
     /**
      * Quote a string so it can be safely used as a table or column name, even if
      * it is a reserved name.

lib/Doctrine/DBAL/Platforms/AbstractPlatform.php

@@ -2092,20 +2092,6 @@ abstract class AbstractPlatform
         return $item;
     }
 
-    /**
-     * Gets the SQL statement specific for the platform to set the charset.
-     *
-     * This function is MySQL specific and required by
-     * {@see \Doctrine\DBAL\Connection::setCharset($charset)}
-     *
-     * @param string $charset
-     * @return string
-     */
-    public function getSetCharsetSQL($charset)
-    {
-        return "SET NAMES '".$charset."'";
-    }
-
     /**
      * Gets the SQL specific for the platform to get the current date.
      *