Public issue https://github.com/mackron/miniaudio/issues/262

This bug results in the first period of samples being pitched at 1.0
regardless of whether or not ma_sound_set_pitch() had been called. What
happens is that the first period is processed at a rate of 1.0, and
then the pitch is applied after the fact. Then, the next period comes
along and resamples at the pitch set by ma_sound_set_pitch() which
results in a harsh sounding glitch.

This was resulting in a loop consuming 100% of the CPU.

Public issue https://github.com/mackron/miniaudio/issues/265

Public issue https://github.com/mackron/miniaudio/issues/265

Public issue https://github.com/mackron/miniaudio/issues/258

These are in preparation for some spatialization functionality.

This does not yet support the following:

  * Cone based attenuation
  * Doppler effect
  * Multiple listeners

This had the naming of source and excite the wrong way around.