Changes to drone spawning

- Drones wait a moment before moving towards the player
- Switch them between rigidBody.isKinematic
Misc Refactoring

- Lots of refactoring throughout
- Renamed SpawnEffects to Particle Manager
- Added player explosion to particle manager
More refactoring

- Tried to make a global instance of bullet pool manager -- working well
-- Global instance of particle manager (from Game Manager) not working
though. Weird.
Moving all spawning logic to spawn manager

- About to move drone spawning there as well
SpawnManager is working awesome

- Tons of refactoring done
- Integrated SwarmBehavior w/  SpawnManager