New Particle System

DO NOT MERGE.
for review.

Defined some classes that can be used for particle:
`Graph<T>`
`LineGraph<T>`
`BezierGraph<T>`
`FloatBezierGraph`
`Gradient`

Add some particle classes:
`Particle`
`ParticleEffector`
`ParticleEmitter`
`ParticleRendererProtocol`
`ParticleTextureAtlasRenderer`