Add advance(numSamples) so the engine can step LFOs per sub-block
instead of calling process() in a sample loop. process() now
delegates to advance(1).
Split phaseOffset from phase so setParams doesn't overwrite the
running phase; getPhase() adds the offset and wraps. Fix sync mode
to divide by beat multiplier instead of multiplying. Move SampleHold
randomization into advance() based on cycle count. Validate shape
data in setShapeData with isfinite and jlimit.
biggy