tabs do not receive proper indentation

Cut-and-paste code with tabs instead of spaces is not displayed with indentation.

I'm terrible at this whole regex thing, but my fix was to add a line (line 71) after

$text = preg_replace("/^\n/", '', preg_replace('@</?(br|p)\s*/?>@', '', str_replace('\"', '"', $text)));

new line:

$text = preg_replace('/\t/', '    ', $text);