reduce waveform scale

Exponentially improves performance (at the expense of higher zoom levels but they were probably already too extreme)

app/widget/timebased/timescaledobject.cpp

@@ -27,14 +27,16 @@
 
 namespace olive {
 
+// Keep this aligned with the kMaximumSampleRate in AudioVisualWaveform
+const double TimeScaledObject::kMaximumScale = 1024;
+
 const int TimeScaledObject::kCalculateDimensionsPadding = 10;
 
 TimeScaledObject::TimeScaledObject() :
   scale_(1.0),
   min_scale_(0),
-  max_scale_(DBL_MAX)
+  max_scale_(kMaximumScale)
 {
-
 }
 
 void TimeScaledObject::SetTimebase(const rational &timebase)