I love the idea of implementing this type of functionality in the wiki project. However, it seems like this particular area of plug-in still needs some maintenance for compliance due to deprecated usages.
The following needs to be updated for markup_e which means I'm sure the source script does also.
Sample usage (from demo page): Please update to markup_e and $m vars.
Markup('mymarkup', 'directives', '/\\(:mymarkup\\s+([^\\s]+)(\\s+.*)?\\s*:\\)/e', "Keep(MyMarkupFunction(\$pagename,'$1',PSS('$2')))");
Thanks, - Marcus 20180416