clean up, add print method for springs, change Euler Function declaration, add demo, demo2 demo3 setup

Simulations/MassSpringSystemSimulator.h

@@ -42,7 +42,9 @@ public:
 	Vec3 calcualtePositionTimestepEuler(Vec3 oldPosition, float timestep, Vec3 veloctiy);
 	Vec3 calcualteVelocityTimestepEuler(Vec3 oldVelocity, float timestep, Vec3 acceleration);
 	Vec3 calculateAcceleration(Vec3 acceleration, float mass);
-	void Euler(int index1, int index2, int indexSpring, float timestep);
+	void Euler(MassPoint& masspoint1, MassPoint& masspoint2, Spring& spring, float timestep);
+
+	void printSpring(const Spring& spring);
 	
 	// Do Not Change
 	void setIntegrator(int integrator) {