Make use of latest Azul3D audio API.

[mewmew]

Updates mewkiz/flac#13.

For background information on the changes to Azul3D and the
audio package, see azul3d/engine#1 and azul3d/engine#76.

[mewmew]

Note, this pull request only updates the Azul3D related functions. E.g. changing uses of audio.F64Samples to audio.Float64 (see issue azul3d/engine#76 for details).

Some functions of waveform are named, following the convention of the old Azul3D audio API (e.g. RMSF64Samples). For consistency, these function names may be updated in the future. To keep the pull request minimal, only Azul3D related changes have been done, but it may be worth keeping in mind. @mdlayher you could decide for yourself, if you wish to update these function names yourself.

Cheers /u

[mdlayher]

Looks great, thanks for the PR!

[Stoyvo]

Thanks @mewmew + @mdlayher ! Quick turn-around time.