wonder if we should add a Points::map method to map coordinates to new values

I am working on something like this which would do that.

I'm not sure I follow, but if @rory does, I'll just wait on the PR!
IMO rotate / translate / skew / scale should all be implemented on top of a more general affine impl that populates an affine transformation matrix with the relevant values depending on the transformation type, but that would require us to pull in a linear algebra crate…

I'm not sure I follow, but if @rory does, I'll just wait on the PR!

for example:

fn translation_matrix<T>(x_offset: T, y_offset: T, points: &[Point<T>]) -> Vec<Point<T>>
    where T: Float
{
    points
        .iter()
        .map(|point| point.map(|x, y| (x + x_offset, y + y_offset))
        .collect::<Vec<_>>()
}

My WIP is here: https://github.com/rory/rust-geo/tree/coord_change. Specifically you can see the file here amandasaurus@b7a01f5 . My idea is to allow you to pass in a function which will take a Coordinate and return a new Coordinate, which gives you maximum flexibility. I don't like the name (coord_change), but can't think of much better.

Maybe map_coords? That's what python-geojson calls it https://pypi.python.org/pypi/geojson#map-coords