* The old implementation was simple but severely limited:
* the resample factor (playback speed) could only be scalar
* for infinite source streams, the algorithm would require infinitely growing memory.
The algorithm therefore also wasn't realtime-safe and quite slow (probably because of reallocations).
* This could be made to work with stream-factors if the source stream is infinite,
but we couldn't get rid of the memory requirements due to being based on IndexStream.
* Instead, there is a custom ResampleStream now that backs Stream:resample().
It also performs linear interpolation but has constant memory requirements and works with factor-streams.
Even for finite source streams and constant factors this implementation will be faster and more
real-time safe.
* You cannot play backwards, due to missing buffering.
This can still be done manually using IndexStream if necessary.