Rebuild Gunship to be completely multi-threaded and have robust support for async operations. The goal is to build async support into the core of the engine and design all functionality with parallelism in mind. This is a major refactor and invalidates pretty much everything in the core engine up to this point. We'll try to re-use as much as possible but a lot of things will need to be rewritten to be thread-safe.

As part of this milestone we'll be removing the existing ECS that's been at the core of Gunship until now. While I'm still personally holding out hope that we can make an ECS work there are too many unanswered questions to make development viable. Instead it will be replaced with a very basic system for interacting with engine-owned resources that will facilitate parallel game code.