Replaced effects with decorators.

Decorators should be way more flexible while beeing easy to use.

RGB.NET.Brushes/Decorators/IGradientDecorator.cs

@@ -0,0 +1,11 @@
+using RGB.NET.Brushes.Gradients;
+using RGB.NET.Core;
+
+namespace RGB.NET.Brushes
+{
+    /// <summary>
+    /// Represents a basic decorator decorating a <see cref="IGradient"/>.
+    /// </summary>
+    public interface IGradientDecorator : IDecorator
+    { }
+}