easing easing iterators for rust

Rust iterators are fantastic—why not use them for easing? Use like so:

use easing;

let begin: f64 = 0;
let end:   f64 = 1000;
let steps: u64 = 10;

// In a for loop!
for x in easing::sin_in(begin, end, steps) {
    println!("Woo, I'm at x={}!", x);
}

// Mapping!
fn move_to(x: f64) {
    println!("Moving on up to {}", x);
}
easing::cubic_out(begin, end, steps).map(move_to);

// And other iterator stuff!
let xs: Vec<f64> = easing::exp_inout(begin, end, steps).collect(); // why would you do this

Available iterators are currently:

function	in	out	in and out
linear	linear	linear	linear
quadratic	quad_in	quad_out	quad_inout
cubic	cubic_in	cubic_out	cubic_inout
quartic	quartic_in	quartic_out	quartic_inout
sinusoidal	sin_in	sin_out	sin_inout
exponential	exp_in	exp_out	exp_inout

Easing functions taken from warrenm's AHEasing.

Find it on crates.io at https://crates.io/crates/easing.

Licesnsed under the LGPLv3.