Add .spz file outputs

[pierotofy]

Should be relatively easy to add support for SPZ files via https://github.com/nianticlabs/spz

[MotivaCG]

It is easy to implement, but notice that the format seems to be a bit abandoned (no new updates), and besides it sounds great it has issues with banding and a small color shifting

[pierotofy]

Agree, we should wait until nianticlabs/spz#21 gets some clarification.