added mounting holes, board ready for export

nore footprint tweaking to meet DRC requirements

ToTheEdge,LCSCNums Moved the 3.5mm connectors to the edge and edited their footprint courtyard so no errors. Adjusted the planes so that it bordered 3.5mm connector pads well and didn't go to edge cuts. Added LCSC part numbers to the parts that were in stock.

Pushed adc connector to edge of pcb

Extended ground planes, rerouted some traces into vias. and pushed connectors to edge of board

Merge pull request #16 from ThaneGallo/jc-layout-work JC Preliminary Layout Work

DRC check passed, but ADC/ADS footprint needs to be checked for JLCPCB compatability (pads may be too close together)

modified footprints and IC silkscreen refereence designators to comply with DRC checks

Final touches to silkscreen on pcb, DRC check still needed

finished majority of layout, pcb expanded to four copper layers to accomadate power planes