this code update will step back from pleateau into peak.

    + okay to slightly over estimate frequency, it will back down to best healthy hashrate.
    + 5-10% increase in hashrate as you return to peak
    + adjust with "--gekko-tune-down" to suit your needs.   [90-95]% is a healthy range, 95 is default, set to 0 to disable.

        1.  Adjusts frequency according to each miner's unique charateristics
        2.  To keep a hash performance above 95%.  
        3.  Based on the idea that (95% of 275MHz) hashes better than (80% of 300MHz)