[Coco] CoCo3 FPGA project analog boards

[Zippster]

I think I have the revisions to the board pretty well done.   Mostly board layout
and routing changes, different DIN connectors, etc.  I replaced the prototyping area
with a header for an optional plug in board, which includes 8 GPIOs from the FPGA,
+3.3v and +5v power, and holes for standoffs to secure the optional board.  I can make
a prototyping PCB to fit if people want that of course, and this way you won’t have to mod
your analog board directly, and the GPIOs will be there without air wires.

It looked like it needed a graphic of some kind for the silkscreen, so for fun
I drew one up.  :)

<https://drive.google.com/open?id=0B1sgl615FlGnM0xmZ2NYVnRqcmM <https://drive.google.com/open?id=0B1sgl615FlGnM0xmZ2NYVnRqcmM>>
<https://drive.google.com/open?id=0B1sgl615FlGnd0NNOTU1Q3FLcW8 <https://drive.google.com/open?id=0B1sgl615FlGnd0NNOTU1Q3FLcW8>>

- Ed