FishLight_PCB: Placed 12V power circuits

Got all of the 12V power circuitry placed in their general locations.
Need to space them out a bit so that I can actually get in there to
solder them and not violate the DRC.  I may need to increase the board
size a bit to fit the AC SSRs
FishLight_PCB: Rearranged some parts

Rearranged the CAT4101s to make more room.  Also changed their screw
terminal assignments to limit the number of crossings.  This will have
to be resolved in software now because the screw terminal assignments
are all screwed around.  Also changed around the Spark to make more room
for the AC SSRs.  These are now placed on the board.  Also moved around
the 12V devices screw terminals and circuitry to limit MUX crossings.
This is going to be super difficult to route and may need to reduce the
number of 12V devices.
FishLight_PCB: Add a README.md file

Adding a README.