changed from thParticle to Particle because there's no thParticle class

src/ofApp.cpp

 	//Birth control for new particles
 	if (birthCount > 0.001) {
 		for (int i = 0;i < 4;i++) {
-			system.push_back(new thParticle);
+			system.push_back(new Particle);
 			system.back()->setup(ofVec2f(ofGetWidth()*.5, ofGetHeight()*.5));
 		}
 		birthCount = 0;

src/ofApp.h

 	float xOfCentroid;
 	float yOfCentroid;
 
-	vector<thParticle*> system;
+	vector<Particle*> system;
 	vector<Attractor*> attractors;
 	float birthCount;
 	double time;