added simple wave classes

To assist the input/output of PCM data, we use the fairly straight-forward
WAVE format. These classes simplify the input and output of such data.

app/decoder/waveinput.h

@@ -0,0 +1,38 @@
+#ifndef WAVEINPUT_H
+#define WAVEINPUT_H
+
+#include <QFile>
+
+#include "render/audioparams.h"
+
+class WaveInput
+{
+public:
+  WaveInput(const QString& f);
+
+  ~WaveInput();
+
+  Q_DISABLE_COPY_MOVE(WaveInput)
+
+  bool open();
+
+  bool is_open();
+
+  QByteArray read(int offset, int length);
+  void read(int offset, char *buffer, int length);
+
+  AudioRenderingParams params();
+
+  void close();
+
+private:
+  bool find_str(QFile* f, const char* str);
+
+  AudioRenderingParams params_;
+
+  QFile file_;
+
+  qint64 data_position_;
+};
+
+#endif // WAVEINPUT_H