Scale waveform when volume is changed

If the volume control is changed the waveform changes as well

Changelog: feature

daisyy-looper/daisyy-looper.ino

@@ -426,7 +426,7 @@ void loop() {
   switch (ui.fx_mode) {
     case FX_MODE_ALL:
       if (!isnan(p5)) {  lfo_amount = p5; }
-      if (!isnan(p6)) {  ui.activeLooper()->volume = p6 * 4.0f; }
+      if (!isnan(p6)) {  ui.activeLooper()->volume = p6 * 4.0f; ui.recalculateWaveform(); }
       if (!isnan(p7)) {  reverbmix = p7; }
       break;
     case FX_MODE_REVERB:

daisyy-looper/ui.h

@@ -873,6 +873,10 @@ class Ui {
       activeLooper()->SetLoop(start, length);
     }
 
+    void recalculateWaveform() {
+      this->waveform_cache_dirty = true;
+    }
+
     private:
       double last_render = 0.0;
       uint16_t waveform_cache[128] = {0};