preg_replace /e modifier

When the excludeheading setting is enabled, PrettyLink uses the /e modifier of the preg_replace function. As this modifier has been deprecated since PHP version 5.5.0 and removed in 7.0.0, all instances where the modifier is used, should be replaced with the preg_replace_callback function.

I.e.
$text = preg_replace('%(<h.*?>)(.*?)(</h.*?>)%sie', "'$1'.insertspecialchars('$2').'$3'", $text);

should be replaced by something like

$text = preg_replace_callback('%(<h.*?>)(.*?)(</h.*?>)%si', function($matches) {
    return $matches[1] . insertspecialchars($matches[2]) . $matches[3];
}, $text);