Sega 9-bin board: put parts of schematic in boxes, add silkscreen labels to back of board, tweaks

Add some patterns to the gitignore file

Align SNES symbol pins to 2.54 mm grid so things can attach to them

Add dual Sega Saturn adaptor using MickGyver's design

Add quad NES adaptor board using MickGyver's design

Add symbols and footprints for NES and SNES sockets

Add dual Sega 9-pin adaptor using MickGyver's design

Add symbol and footprint (with 3D model) for Arduino Pro Micro

Start with gitignore file