fix broken substr return in replacements.php

[JungleGenius]

Hi Adrian Happy Holidays,

Here is a pull request to fix the currently broken the {substr.{replacement}} code.

Also I think you should rethink the replacement caching because I had to hack my theme's functions.php with the following just to to deal with stale replacement values:

function disable_replacements_cache_for_form_page() { wp_cache_set( 'last_changed', microtime(), 'groundhogg/replacements' ); }

add_action( 'groundhogg/replacements/init', 'disable_replacements_cache_for_form_page');

Admittedly I was using {substr.{replacement}} on {GET.url_param} I don't think my use case is too unique.

Hopefully this can get merged into the main branch soon so I don't have to use a hacked plugin for too long in production.

Also as you don't have a public repo for the groundhogg contracts plugin I'm posting a screen shot of the edit required to fix the print button to work. It look like JQuery was not getting loaded so I added the wp_enqueue_script for it.

I hope you can get this added to your non-public repo. Thank for the great product.

-Daniel