Refactor SECLAL player into new threaded player class

The reason for moving the implementation out from CSoundGenerator into
its own class is, because CSoundGenerator was a very complex and
obscure class. It mixed many tasks in one place. CSelcalPlayer
is designed to play SELCALs only.

The following design changes have been made, compared to CSoundGenerator:
* Use pull mode instead of push mode. QBuffer is used as the QIODevice and
  is a wrapper around QByteArray. Therefore it is not necessary to
  implement our own QIODevice.
* Internally it uses a CThreadedSelcalPlayer to relieve the load of the
  main thread. CThreadedSelcalPlayer inherits CContinuousWorker, no
  low level QThread implementation was necessary.
* Push mode was not implemented.
* It is important that the QAudioOutput is allocated in the worker thread.
  QAudioOutput allocates internal objects, which cannot be moved to
  the worker thread.
* Data caching. The generated seclal audio data is cached.

refs #736

src/blacksound/tonepair.cpp

@@ -0,0 +1,22 @@
+/* Copyright (C) 2016
+ * swift project Community / Contributors
+ *
+ * This file is part of swift project. It is subject to the license terms in the LICENSE file found in the top-level
+ * directory of this distribution and at http://www.swift-project.org/license.html. No part of swift project,
+ * including this file, may be copied, modified, propagated, or distributed except according to the terms
+ * contained in the LICENSE file.
+ */
+
+#include "tonepair.h"
+
+namespace BlackSound
+{
+    CTonePair::CTonePair(const BlackMisc::PhysicalQuantities::CFrequency &frequency,
+          const BlackMisc::PhysicalQuantities::CFrequency &secondaryFrequency,
+          const BlackMisc::PhysicalQuantities::CTime &duration) :
+        m_firstFrequencyHz(static_cast<int>(frequency.valueRounded(BlackMisc::PhysicalQuantities::CFrequencyUnit::Hz()))),
+        m_secondFrequencyHz(static_cast<int>(secondaryFrequency.valueRounded(BlackMisc::PhysicalQuantities::CFrequencyUnit::Hz()))),
+        m_durationMs(static_cast<qint64>(duration.valueRounded(BlackMisc::PhysicalQuantities::CTimeUnit::ms())))
+    { }
+
+}