Fix compilation in 2D.

src/geometry/collider.rs

@@ -4,8 +4,6 @@ use crate::geometry::{ColliderShape, InteractionGroups};
 use crate::math::{AngVector, Isometry, Point, Real, Rotation, Vector, DIM};
 use cdl::bounding_volume::AABB;
 use cdl::shape::Shape;
-#[cfg(feature = "dim2")]
-use cdl::shape::{ConvexPolygon, RoundConvexPolygon};
 
 bitflags::bitflags! {
     #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]