Project Loader + Operation types

Added the concept of a “Project” which is a collection of “Studios”. When you open the app you select a project directory and it will look at the files in it to load each Studio. This also unlocks persistent storage and multi-studio projects.

One limitation is it relies on the Filesystem API which Firefox doesn’t support for security reasons. That is a bummer, but since the primary target for this app is anyways native it shouldn’t matter too much.

I also implemented operation types for extrudes, including negative and intersection operations.