Tasty FFT spiral demo for the 32x16 panel

Music not included this time, sadly.
Fix submodule target path in the server Makefile.

Signed-off-by: Jérôme Benoit <jerome.benoit@grenouille.com>
Port attractor demo to 32x16 grid
Adjust parameters for better pacing
New "ember" example, contributed by April Arcus
Add a really simple burn-in test helper
Update fc64x8 CAD files with final design from Adafruit

- Remove outdated BOM file (Adafruit doesn't use a separate BOM spreadsheet)
- Added fiducials
- Added Adafruit logo
Python 3 compatibility
Style cleanup
Variant of grid32x16z_particle_fft using line input
OPC-style JSON layout files for some example LED grids
Particle trail example for Node.js

Shows easy and high quality particle animation with JavaScript
Update README.md
New diagrams

Details of how fcserver and the controller operate
Adding testjig PCB contributed by Ryan O'Hara
Mention CAD packages in README
Make loadModel() a static method
Add a triangle FFT visualizer tweaked for mic input
HSV color for opc.js
New particle system example in Node.js