Rename "flutter" to "drift"

oscillator.cpp

@@ -5,6 +5,6 @@ Oscillator::Oscillator() {
     phase = 0;
     phaseStep = (440 * 2 * M_PI) / 44100;
     value = 0;
-    flutterSpread = 0.005;
-    flutter = 0;
+    driftAmount = 0.005;
+    driftValue = 0;
 }

oscillator.h

@@ -11,12 +11,11 @@ public:
     enum Mode { MODE_SINE, MODE_SAW, MODE_SQUARE };
 
     Mode mode;
-    float phase;        // current waveform phase angle (radians)
-    float phaseStep;    // phase angle step per sample
-    float value;        // current amplitude value
-    float flutterSpread;
-    float flutterSpeed;
-    float flutter;
+    float phase;            // current waveform phase angle (radians)
+    float phaseStep;        // phase angle step per sample
+    float value;            // current amplitude value
+    float driftAmount;
+    float driftValue;
 
     Oscillator();
 
@@ -63,8 +62,8 @@ public:
             value -= polyBlep(fmod(t + 0.5, 1.0)); // Layer output of Poly BLEP on top (flop)
         }
 
-        flutter += 0.01 * ((float) rand() / RAND_MAX - 0.5) - 0.00001 * flutter;
-        phase += phaseStep * (1.0 + flutterSpread * flutter);
+        driftValue += 0.01 * ((float) rand() / RAND_MAX - 0.5) - 0.00001 * driftValue;
+        phase += phaseStep * (1.0 + driftAmount * driftValue);
         if(phase >= PIx2) { // wrap if phase angle >=360º
             phase -= PIx2;
         }