Update PCB README and Off_PCB_Connections Added FET to README and Off_PCB_Connections

Tweak to FET step-by-step doc Added note to make sure FET2 and FET3 metal backs are not touching each other and added resistance test between FET2 and FET3 metal backs.

Update copyright Updated the copyright dates in the IV_Swinger2.ino file header

Optimize Isc measurement for SSR/FET hardware (Issue #181) Changed the algorithm that determines when Isc is stable so that when the hardware uses SSRs or FETs, the polling ends when the current and voltage stop changing (when SSR3/FET3 is on). Previously, when this condition occurred, the polling would continue, using the EMR algorithm. But this always resulted in an Isc point further away from the axis, meaning a larger extrapolation. The tricky part is that the code doesn't know if the hardware is EMR or SSR/FET. But the EMR conditions won't occur on SSR/FET hardware and the SSR/FET conditions won't happen on EMR hardware, so the code just looks for both of them in parallel, and the polling naturally terminates at the correct time for the given hardware. Updated version number to 1.4.4

Fix FET step-by-step doc and add PDF Fixed some bad page breaks. Updated the TOC so it has hyperlinks in the PDF. Added the PDF.

Update IV_Swinger2_FET_mod_PCB_Step_by_Step.docx File had not been saved in Word in previous commit. Very minor diffs.

New files for FET version (Issue #179) Add initial versions of FET version PCB files, BOM, and step-by-step instructions

Fix minor debug feature issue No Issue was filed for this. There is a debug feature that skips Isc polling if max_isc_poll is negative. For some reason, adc_i_val_prev_prev was set to 2048 in the code that handles this. Since that value is used for isc_adc, the Isc point has an ADC value of 2048 regardless of the measured points. adc_i_val_prev_prev is now set to adc_i_val instead.

Assure that SSR3/FET3 cannot stay active (Issue #180) Unconditionally turn off SSR3/FET3 after the Isc polling loop

Add Arduino sketch support for FET version (Issue #179) Support is added to the Arduino sketch for the upcoming FET version of IVS2. This code is completely compatible with the other IVS2 versions. The only change is that a new Arduino digital pin (D9) is used to control FET3 because it is active-high, whereas SSR3 is active-low.