replacement es5 functions to es6 classes feat p5.Oscillator (#533)

* replacement es5 functions to es6 classes feat p5.Oscillator

* corrected SigChain  def from class to function and removed unwanted consoles

Author: endurance21

src/app.js

@@ -28,7 +28,14 @@ import FFT from './fft';
 p5.FFT = FFT;
 
 import './signal';
-import './oscillator';
+
+import Oscillator, { SinOsc, TriOsc, SawOsc, SqrOsc } from './oscillator';
+p5.Oscillator = Oscillator;
+p5.SinOsc = SinOsc;
+p5.TriOsc = TriOsc;
+p5.SawOsc = SawOsc;
+p5.SqrOsc = SqrOsc;
+
 import './envelope';
 
 
@@ -95,8 +102,6 @@ import peakDetect from './peakDetect';
 p5.peakDetect = peakDetect;
 
 
-
-
 import SoundRecorder from './soundRecorder';
 p5.SoundRecorder = SoundRecorder;