NES Arduino PCB - v0.3

So I'm kind of enjoying the revision process.

The original designs were using the digital outputs from 0-14. This is still good for using everything internal to the Arduino, but 0 and 1 are used for serial communication. Don reminded me of the potential of using the PC for control, so I remade the board with a few changes.
- Digital pins 2-13 are used (12 bits of control) to free up serial communication
- The MSB is properly wired, this is something I had fixed in software, but now the pins are mapped more naturally (LSB of arduino matches LSB of button register after latch/clocks)
- I still used the ground plane, but with more isolation to avoid bridging any soldering points (again)

I'm writing up a diagnostic tool to verify that everything is being received properly. I'll use it for any boards I produce after to make sure all the bits are working.