Allow \x1b (ascii ESC) in wfDebug() output

Allow \x1b (ascii ESC) in wfDebug() output

It is a local hack I had to let me pass colored debug message using a local
wrapper:

function wfDebugGreen($msg) {
	$color = "\x1b[1;32m"; # Green
	$reset = "\x1b[1;0m";
	wfDebug( $color . $msg . $reset );
}

Ideally \x1b should only be kept if it is followed by /(\d+(;\d)?)?+m/
which should match the 'graphic rendering' ANSI escape code.