1. in storeDataToFile()
      - changed name of the thread
2. in audio_buffer_full()
      - added *data parameter recognition
      - removed redundant code
3. in audioSource()
      - changed stream naming to PID+index
      - bug fix in openStream() params passing, added 'm_options' as user 'params' to
        recognize stream-callback relation in audio_buffer_full()
      - removed redundant 'm_audio_buffer_bytes' variable
deleted unused data member
changed init order
added button functionality to start/stop audio callback time statistics
added statistic of audio callback timing
removed unnecessary static variables, replaced by one static interface function where signal is processed
changed function name, reordered function definition in file
removed redundant include