Lathe places EQ bands on harmonics 1-32 of the played note, so a cut on
harmonic 3 stays on harmonic 3 on every note. Temper normalises each
note's level before an oversampled shaper and tunes its floor, push and
bright filters to the note, so every note distorts the same.
The note tracker moves from Anvil into common-dsp, together with a
state-variable filter, 4x oversampler and harmonic meter. Anvil's
behaviour and editor render are unchanged.
docs/ideas.md collects all plugin ideas and their status.
