The constructor of the class `IkJoint` should also work with joints that are not created by `urdf-loader`.

[pinglu85]

Currently, the constructor of the class IkJoint only accepts joints that are created by urdf-loader or null. It should also work with hard coded joints, for instance,

const firstJoint = {
  localPosition: [0, 0.11, 0],
  axis: [0, 1, 0],
  limit: [-170, 170],
};