Update EL Wire firmware

This is already version 3, which adds a few features and fixes a few
bugs:

- Add posibility to rename Bluetooth devices
- Add commands for Strobe and Fade (in+out); cooperative multitasking
  has been implemented to allow controlling more than one wire at "the
  same time". Up to three tasks can be cooperatively scheduled, and
  scheduler is executed when in idle and not receiving data from Bluetooth
  module
- FadeIn/FadeOut uses an exponental function. For some reason, a linear
  function didn't work as expected, so a LUT is provided to map luminosity
  percentage to PWM value to be used with analogWrite()
- Sending commands to Bluetooth now take into account needed delays. This
  fixes bugs where HC06 responses would trigger state changes and keep the
  Arduino in some unknown state. This happens with some modules but not
  with all of them. So far the timeouts used here are working are sufficient
  for all tested modules