Multithreaded Danmaku Processing

[james7132]

Currently all of the danmaku object updates are entirely single threaded. A great performance boost should be attainable by multithreading each update.

Several parts are required:

• Minimize the number of Unity API calls needed to be made in each update
• Create an effective alternative threadpool, since Unity Mono doesn't have one that actually works effectively.

[james7132]

It seems that switching to Particle Systems has already multithreaded the rendering of the bullets, and almost everything outside of collision checks are thread-safe now. A bit of reordering of events and it shouldn't be too hard to use a thread pool to calculate danmaku movement.

[james7132]

Handled by the new C# job system.