Helper functions
- Added Fmod PCM data > Byte array function (PrepFmodForFft())
- Added PCM to FFT data function (PcmToFft())
- Added function to plot waveform to an image, inaccurate but good
  enough for intended use (WaveFormImage())
- Added IsPowerOfTwo() function (guess what it does)
- Made Fmod error checking more simple
- Added WAV structures from the Fmod RecordToDisk demo, for saving files
  with wave headers attached