message: add layer function
diff: @@ -114,6 +114,21 @@ namespace MakerJs.path {
  return mirrored;
  };
  + /**
  + * Set the layer of a path. This is equivalent to:
  + * ```
  + * pathContext.layer = layer;
  + * ```
  + *
  + * @param pathContext The path to set the layer.
  + * @param layer The layer name.
  + * @returns The original path (for cascading).
  + */
  + export function layer(pathContext: IPath, layer: string): IPath {
  + pathContext.layer = layer;
  + return pathContext;
  + }
  +
  /**
  * Create a clone of a path, mirrored on either or both x and y axes.
  *
  