added clamping diode D6 per Paul's recommendation, to help protect U17

also reduced pad size on ADC footprint to help prevent solder bridging updated a few footprint silkscreens to more closely match original rev3 board added note in control board schematic recommending U26 Pin 2 trace length minimization generated updated gerber zip files TODO: update IC pads to match more closely to original rev3 board if it will make soldering easier