WIP: Support 4 daisy-chained 32x32

- Moved frame buffers to extended memory space.
- Made them 4x larger.
- Made protocol message buffer larger (to fit a whole frame).
- Avoid an extra copy while reading from file - read directly to
  back-buffer.
- Temporary: slowed down frame rate 2x. Should be able to increase back
  up, but not to the same rate as before. Need to calculate the ideal
  rate.
- Changed the protocol to allow a wider row-length range. Was limited to
  32 x 3-bit value. Now 32 x 8-bit.