Feature Suggestion

Feature description:

Hatched fills can be easier to read, especially for colourblind users or when printed in black and white. See #1940 (comment), and also #555

Code example: If applicable, use this space to demonstrate how you wish the new feature could be used in code.

pie.SliceHatches = new[] {Drawing.HatchStyle.StripedWideUpwardDiagonal, Drawing.HatchStyle.StripedWideDownwardDiagonal, Drawing.HatchStyle.LargeCheckerBoard }

This would also need a SliceHatchColor field, which makes me wonder if this should be replace with a HatchOptions struct:

struct HatchOptions {
  public HatchStyle HatchStyle { get; set; }
  public Color HatchColor { get; set; }
}

I will probably defer to what Bar plots do (keeping them as separate fields) for consistency's sake, but I thought I'd bring it up in case someone had an opinion.