Rev 2 Schematic and BOM

TODO before design review:

[ ] Adjustable regulator enable pin should be wired to the mcu with a pull down
[ ] Label all test points
[ ] Add additional ground loops for probing, and possibly a solderable ground plane?
[ ] Reduce status led brightness
[ ] Reduce all blue led brightnesses (maybe switch to 2Kohm?)
[ ] Fix programming header reset pin
[ ] Change some test points to thru hole or probe loop style
[ ] Fix pull-up/pull-down dual transistor footprint
[ ] Fix DAC logic level shift/scale voltage divider (eliminate cascaded voltage dividers)
[ ] Lower all pull-up/pull-down and op-amp feedback resistors an order of magnitude

csinko / io-master