renderer: fixed bug that would render frames even after hash matching

Also enables the -Wshadow GCC warning to warn against the code bug that
caused this issue (and has caused other issues like it in the past).

app/widget/audiomonitor/audiomonitor.cpp

@@ -90,11 +90,11 @@ void AudioMonitor::Stop()
   }
 }
 
-void AudioMonitor::OutputPushed(const QByteArray &data)
+void AudioMonitor::OutputPushed(const QByteArray &d)
 {
   QVector<double> v(params_.channel_count(), 0);
 
-  BytesToSampleSummary(data, v);
+  BytesToSampleSummary(d, v);
 
   PushValue(v);
 

app/widget/audiomonitor/audiomonitor.h

@@ -45,7 +45,7 @@ public slots:
 
   void Stop();
 
-  void OutputPushed(const QByteArray& data);
+  void OutputPushed(const QByteArray& d);
 
 protected:
   //virtual void paintEvent(QPaintEvent* event) override;

app/widget/menu/menu.cpp

@@ -50,13 +50,13 @@ Menu::Menu(const QString &s, QWidget *parent) :
   Init();
 }
 
-QAction *Menu::AddActionWithData(const QString &text, const QVariant &data, const QVariant &compare)
+QAction *Menu::AddActionWithData(const QString &text, const QVariant &d, const QVariant &compare)
 {
   QAction* a = addAction(text);
 
-  a->setData(data);
+  a->setData(d);
   a->setCheckable(true);
-  a->setChecked(data == compare);
+  a->setChecked(d == compare);
 
   return a;
 }

app/widget/menu/menu.h

@@ -132,7 +132,7 @@ public:
   }
 
   QAction* AddActionWithData(const QString& text,
-                             const QVariant& data,
+                             const QVariant& d,
                              const QVariant& compare);
 
   QAction *InsertAlphabetically(const QString& s);

app/widget/timelinewidget/timelinewidget.cpp

@@ -1584,9 +1584,9 @@ bool TimelineWidget::SnapPoint(QList<rational> start_times, rational* movement,
 
   // Find all points at this movement
   QList<rational> snap_times;
-  foreach (const SnapData& data, potential_snaps) {
-    if (data.movement == *movement) {
-      snap_times.append(data.time);
+  foreach (const SnapData& d, potential_snaps) {
+    if (d.movement == *movement) {
+      snap_times.append(d.time);
     }
   }