Delete faders when destroying CAudioMixerBoard.

This avoids a harmless memory leak.

src/audiomixerboard.cpp

@@ -704,6 +704,14 @@ CAudioMixerBoard::CAudioMixerBoard ( QWidget* parent, Qt::WindowFlags ) :
     connectFaderSignalsToMixerBoardSlots<MAX_NUM_CHANNELS>();
 }
 
+CAudioMixerBoard::~CAudioMixerBoard()
+{
+    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+    {
+        delete vecpChanFader[i];
+    }
+}
+
 template<unsigned int slotId>
 inline void CAudioMixerBoard::connectFaderSignalsToMixerBoardSlots()
 {

src/audiomixerboard.h

@@ -169,6 +169,8 @@ public:
     CAudioMixerBoard ( QWidget*        parent = nullptr,
                        Qt::WindowFlags f      = nullptr );
 
+    virtual ~CAudioMixerBoard();
+
     void HideAll();
     void ApplyNewConClientList ( CVector<CChannelInfo>& vecChanInfo );
     void SetServerName ( const QString& strNewServerName );