Give option to not remove vertices when constructing ConvexPolyline and other such shapes

[Ughuuu]

Right now if I create a ConvexPolygon I use from_convex_polyline, however sometimes this will remove some points. Give option to not remove the points (eg. default constructor or simpler constructor).

[WaffeFIN]

I too have this issue. I would suggest a change to the epsilon used in _from_convexpolyline making it much smaller:

let eps = 2.0 * crate::math::DEFAULT_EPSILON;

It would be nice to have the tolerance/epsilon as a parameter, in which case it could be disabled by making it zero. I bet that change would be quite disruptive though.

Related to this matter, here are also some unit tests I've added to my local version of parry2d (convex_polygon.rs):

#[test]
fn test_convex_polyline_for_stretched_quad() {
    let vertices = vec![
        Point::new(-35.0, 0.0),
        Point::new(38.0, 0.0),
        Point::new(39.0, 1.0),
        Point::new(17.0, 1.0), 
    ];
    let expected_points = [
        Point::new(-35.0, 0.0),
        Point::new(38.0, 0.0),
        Point::new(39.0, 1.0),
        Point::new(17.0, 1.0), 
    ]; // No change

    let collider = ConvexPolygon::from_convex_polyline(vertices).unwrap();

    assert_eq!(collider.points(), expected_points);
}

#[test]
fn test_convex_polyline_for_basicly_triangle() {
    let vertices = vec![
        Point::new(-1000.0, 0.0),
        Point::new(1000.0, 0.0),
        Point::new(1000.0, 1.0),
        Point::new(-0.01, 0.5), 
    ];
    let expected_points = [
        Point::new(-1000.0, 0.0),
        Point::new(1000.0, 0.0),
        Point::new(1000.0, 1.0),
    ];

    let collider = ConvexPolygon::from_convex_polyline(vertices).unwrap();

    assert_eq!(collider.points(), expected_points);
}