[WIP] Add support for PWM resolutions other than 8-bit

[dtex]

Required for ESP32. Addresses #1275, #1276, and #1280

[rwaldron]

Can we do a pass on this file and change __ to Fn? Probably in another patch?

[DanHartman]

I do not understand how to access the 12 bit resolution of the PCA9685.
I suspect that I have misinterpreted what pwmRange does.
Given the following code, I expected to see a duty cycle on my oscilloscope that is a fraction of full on.
What I see is near full scale output that would imply that my value of 254 is almost max 8 bit resolution.
What have I done wrong?

const five = require('johnny-five')

five.Board().on('ready', function() {
  var led = new five.Led({
    pin: 0,
    controller: 'PCA9685',
    pwmRange: [0, 4095]
  })
  led.brightness(254)
})