arduino-copilot-1.1.1: TODO

* analogReference()
  Takes one of a set of defines, which vary depending on board,
  so how to pass that through Copilot? Could write a C
  switch statement, on an int, and have the boade modules define
  effectively enums.
* readvoltage gets a raw ADC value; add a stream function to convert that
  to a floating point actual voltage, given also a stream that contains
  the reference voltage.
* delayMicroseconds
* random numbers
* Wire library