Added promises.js and polyfills.js and added option for combining
Added mod_includes for css and js and mod_rewrite for bad requests
Corrected my logic and includes.

Load only combined.js if $site->debug
New file, uses mod_included to load all js as single file
Removed 'use strict' for when included via mod_includes
Promises polyfill included
Include all css via mod_includes
Turn on debugging
More magic! MutationObservers, eventListeners, XMLHttpRequests, Promises all work together

Also, use FormData(form) in xhr.send() instead of building request manualy.