Filter.php

<?php

function Filter($data, $control = true, $encoding = null)
{
	if (is_array($data) === true)
	{
		$result = array();

		foreach ($data as $key => $value)
		{
			$result[self::Filter($key, $control, $encoding)] = self::Filter($value, $control, $encoding);
		}

		return $result;
	}

	else if (is_string($data) === true)
	{
		if (is_null($encoding) === true)
		{
			$encoding = 'UTF-8';
			
			if (extension_loaded('mbstring') === true)
			{
				$encoding = mb_detect_encoding($data, 'auto');
			}
		}
		
		$data = @iconv($encoding, 'UTF-8//IGNORE', $data);

		if ($control === true)
		{
			return preg_replace('~\p{C}+~u', '', $data);
		}

		return preg_replace(array('~\r[\n]?~', '~[^\P{C}\t\n]+~u'), array("\n", ''), $data);
	}

	return $data;
}

// http://stackoverflow.com/questions/910793/php-detect-encoding-and-make-everything-utf-8

?>

For those of you wondering what the ending regex is all about, see the manual on unicode control characters added to PREG in PHP 5.1.