Major cleanup

Wrap themizer.js in IIFE, replace repetitive code with functions, fix
bug where changing pages on a non-Core theme would style everything

Also fixes #11.
Change inputs on style change, bugfixes
Bugfixes, improve dev mode

Copy code to variable instead of element to avoid lag whenever the user
types
Add protection against hiding/transforming body/html
Minor fixes for protection system
Change protection system

Now modifies the selector to select the preview instead of just silently
discarding the offending property.
Use AJAX to update Try-It
Merge branch 'feature/load-styles-with-ajax' into develop

Conflicts:
	css/slidersidebar.min.css
	js/script.js
	src/css/slidersidebar.css
	src/js/script.js