message: lighten and darken blend modes implemented
diff: @@ -84,21 +84,22 @@ impl From<BlendMode> for Blend {
  destination: Factor::One
  },
  alpha: BlendChannel {
  - equation: Equation::Sub,
  - source: Factor::One,
  - destination: Factor::One
  + equation: Equation::Add,
  + source: Factor::ZeroPlus(BlendValue::SourceAlpha),
  + destination: Factor::OneMinus(BlendValue::SourceAlpha)
  },
  },
  BlendMode::Darken => Blend {
  color: BlendChannel {
  - equation: Equation::Sub,
  + equation: Equation::Min,
  source: Factor::One,
  destination: Factor::One
  },
  alpha: BlendChannel {
  - equation: Equation::Sub,
  - source: Factor::One,
  - destination: Factor::One
  +
  + equation: Equation::Add,
  + source: Factor::ZeroPlus(BlendValue::SourceAlpha),
  + destination: Factor::OneMinus(BlendValue::SourceAlpha)
  },
  },
  }
  