This is private at the moment, but may be made public later.

This is done in preparation for some documentation generation and also
to get it out of the way of the part of the documentation that explains
how to use the library.

This is useful for those only using miniaudio for data conversion,
decoding and/or encoding.

Public issue https://github.com/dr-soft/miniaudio/issues/171

Public issue https://github.com/dr-soft/miniaudio/issues/171

Public issue https://github.com/dr-soft/miniaudio/issues/171

Public issue https://github.com/dr-soft/miniaudio/issues/172

I've noticed that a lot of this doesn't actually require atomic
operations so this may be reviewed again later.