Changed the name of class 'Particle' to 'Entity'
Merge branch 'master' of https://github.com/romrz/MathJetpack

Conflicts:
	src/mathjetpack/Game.java
	src/mathjetpack/entity/Entity.java
	src/mathjetpack/map/Map.java
	src/mathjetpack/particle/Entity.java
	src/mathjetpack/particle/Particle.java
	src/tests/BasicParticleTest.java