Bring Analog API to life

[aethaniel]

No description provided.

[logos-electromechanical]

I'm working on this for SAM4S now and I've noticed that it would be extremely convenient to have a couple of things...

1. Define the peripheral used for PWM or Timer on that pin in the PinDescription somewhere other than the ulPinType member. This is because, at least for the Arachnio, I share some pins between PWM/Timer output and a different function. This will require at a bit of work for each variant. Thoughts?

2. Copy over some utility functions from libsam to a common location. In particular, it would be nice to have PIO_SetPeripheral() and I suspect others as well. I was considering dragging it over as a local function for core_analog, but I realized that I'm going to want it other places as well. How do folks feel about adding a core_utils.{h|c} for this and similar functions?

[logos-electromechanical]

Assuming no comments, I will test my implementation of this this weekend and then generate a pull request.

[aethaniel]

sorry to be late on this, your questions raise interest. I have to invest on this to answer you properly.