Experiments in the controller, and now buildable in Arduino v1.6.6+

Made up a new code bundle, wrapping up a couple of recent changes.

Firmwares are now all buildable in Arduino IDE v1.6.6+.
The polargraph_server_polarshield firmware now uses the same kind of communications protocol as the _a1 variation. This is a little experimental, so let’s give it a shot.
The controller console is back! In a bit of a reduced form anyway. We’ll see if it’s worth anything. Ctrl-C.
There’s a posterisation option for the pixel density preview. You might use this to visualise how a compressed dynamic range will affect your drawing. You get a compressed dynamic range when you use very small grid size, or a big pen. It’s not linked to pen size yet, but that’s the obvious thing to do next.

Polargraph