Convolution & npot-scales

[dy]

Generic multiscale approach is convonving with some kernel and subsequent resampling (for the appropriate scale). The problems of it is computational complexity (more than O(NlogN), unless we reuse subscales relation), which is better done with webgl or SIMD etc, which is too heavy for the simple thing.

That would allow for dy/gl-waveform#9, because difference of pot2 scales is too prominent; and for future NN works.