Waterfall jitter and cumulative runtime issues

[cjcliffe]

The new waterfall code appears to be jittering (dropping frames) as well as a frame rate slowdown that appears to occur after a long runtime.

My best guess is some bad thread access to a ReBuffer object in the new visual code; I'm going to review and try to fortify everything involved to be thread safe and perform boundary checks.

Additionally the new FFTDataDistributor has no overflow container; some of the FFT bits are being lost due to misalignment with the current view.