ina219

INA219 current/power monitor driver for Rust

Example

```rust extern crate ina219; extern crate linuxembeddedhal as hal;

use hal::I2cdev; use ina219::{INA219, INA219_ADDR};

fn main() { let device = I2cdev::new("/dev/i2c-1").unwrap(); let mut ina = INA219::new(device, INA219_ADDR);

ina.calibrate(0x0100).unwrap();

let voltage = ina.voltage().unwrap();
println!("bus voltage: {:?}", voltage);

let shunt_voltage = ina.shunt_voltage().unwrap();
println!("shunt voltage: {:?}", shunt_voltage);

let current = ina.current().unwrap();
println!("current: {:?}", current);

let power = ina.power().unwrap();
println!("power: {:?}", power);

}

```