Create buffer class that replaces the BufferSet struct

Move the fixes from the SFAP library's stream.c to this one

Think a lot about how multichannel streams are to be handled. Doing it all in one thread might not be possible so perhapse a built-in synchronisation system is worth it?

Think about how blocks handle multi-channel streams. Maybe sometimes you want different behavior for each channel, so duplicating the DSP as is could be stupid

Using multiple threads for audio may be slower than interleaved channels. It could also add latency since it has to be re-interleaved at the end of the DSP.