add initial velocity to newtonian particle influencer

Author: riccardobl

jme3-core/src/main/java/com/jme3/effect/influencers/NewtonianParticleInfluencer.java

@@ -80,6 +80,7 @@ public void influenceParticle(Particle particle, EmitterShape emitterShape) {
             // adding tangent vector
             particle.velocity.addLocal(temp);
         }
+        particle.velocity.addLocal(initialVelocity);
         if (velocityVariation != 0.0f) {
             this.applyVelocityVariation(particle);
         }