Implement modding support for web builds

[EliteMasterEric]

trafficstars

Adding modding support for HTML5 browser games is a fun idea.

However, what should the user experience for this look like? Do we somehow have to have the user select a ZIP file on their computer, completely negating the benefits of instant download game development? Do we add essentially a CurlFileSystem where people add mods by providing a URL for the game to perform CORS to download and extract into memory?

Once we know that, we can implement a new file system and a sample to build in HTML5.