Fix Mousewheel support

src/panel/MeterPanel.cpp

@@ -74,6 +74,14 @@ void MeterPanel::setRange(float low, float high) {
     this->high = high;
 }
 
+float MeterPanel::getLow() {
+    return this->low;
+}
+
+float MeterPanel::getHigh() {
+    return this->high;
+}
+
 void MeterPanel::setValue(float value) {
     if (value > high) {
         value = high;

src/panel/MeterPanel.h

@@ -10,6 +10,8 @@ public:
     void setName(std::string name_in);
     std::string getName();
     void setRange(float low, float high);
+    float getLow();
+    float getHigh();
     void setValue(float value);
     void setHighlight(float value);
     void setHighlightVisible(bool vis);