UI system

S&box's UI system is designed as a HTML and CSS parser linked to C# code.

This approach was chosen for the following benefits:
 * No need to code one's own UI system
 * No need to code one's own Font system
 * No need to code one's own Styles system
 * No need to code one's own UI Animation system
 * No need to code one's own Video system
 * HTML is already used everywhere
 * Lots of tools exist to edit HTML
 * Styling is easy, fast, versatile
 * Animations are easy, fast
 * Effects like text shadow are easy, fast
 * Learning html/css/js is a transferable skill
 * Automatically multithreaded
 * Forced separation of view/model/controller

The system is component based. Rather than making a large page, smaller components are created that will work together using the Vue Javascript library. It will be capable of hotloading components.