Update .emitParticles()

[Mophyr]

• Solve issue with emit count argument not passing to descending ParticleEmitters
• Removed EmitDuration functionality since it serves no purpose considering :Emit() only emits at the time of call
• Return array of delayed threads for emitters with EmitDelay attribute in case the user wants to clean them up (use case: cancel those threads in case emitter no longer exists before the delay time elapses)

[Raild3x]

Included in latest version