Waveform generation trait

[Kixunil]

I'd like to propose a waveform generation trait. This would be useful for efficient bitbanging, PWM, etc.

I will begin with simple sketch and we will see where it will lead.

pub struct Microseconds(/*What should go here? Maybe `pub u32` is fine?*/);

pub enum PinState {
    High,
    Low,
}

pub trait WaveGen {
    fn generate<I: Clone + IntoIterator<Item=Microseconds>>(&mut self, pin: Pin, initial_state: PinState, delays: I, repeat_count: u32);
}

The implementor should set the pin into state defined by initial_state, then wait for duration specified by item from delays and toggle the pin after each item.

I'd love to implement some drivers for wireless sockets I have.