Add faster and more accurate WindowedSinc interpolators.

[psobot]

Fixes #142.

Fixes the aliasing problem, while also speeding up resampling operations by between 2x and ~20x depending on the sample rates involved. Faster than the lovely resampy library in many cases, with similar quality, while still using constant memory.

These three graphs do the talking:

TODO:

• Set the new default to WindowedSinc32
• Update documentation with these graphs and recommendations
• Clean up some of the new SIMD code (commented-out experiments)
• Add graphing code from the above graphs