Streamline tree API a bit

src/Spectre.Console/Rendering/ITreeRendering.cs

@@ -1,20 +0,0 @@
-namespace Spectre.Console.Rendering
-{
-    /// <summary>
-    /// Represents the characters used to render a tree.
-    /// </summary>
-    public interface ITreeRendering
-    {
-        /// <summary>
-        /// Get the set of characters used to render the corresponding <see cref="TreePart"/>.
-        /// </summary>
-        /// <param name="part">The part of the tree to get rendering string for.</param>
-        /// <returns>Rendering string for the tree part.</returns>
-        string GetPart(TreePart part);
-
-        /// <summary>
-        /// Gets the length of all tree part strings.
-        /// </summary>
-        int PartSize { get; }
-    }
-}

src/Spectre.Console/Rendering/Tree/AsciiTreeAppearance.cs

@@ -5,10 +5,13 @@ namespace Spectre.Console.Rendering
     /// <summary>
     /// An ASCII rendering of a tree.
     /// </summary>
-    public sealed class AsciiTreeRendering : ITreeRendering
+    public sealed class AsciiTreeAppearance : TreeAppearance
     {
         /// <inheritdoc/>
-        public string GetPart(TreePart part)
+        public override int PartSize => 4;
+
+        /// <inheritdoc/>
+        public override string GetPart(TreePart part)
         {
             return part switch
             {
@@ -18,8 +21,5 @@ namespace Spectre.Console.Rendering
                 _ => throw new ArgumentOutOfRangeException(nameof(part), part, "Unknown tree part."),
             };
         }
-
-        /// <inheritdoc/>
-        public int PartSize => 4;
     }
 }

src/Spectre.Console/Rendering/TreeRendering.cs

@@ -1,13 +0,0 @@
-namespace Spectre.Console.Rendering
-{
-    /// <summary>
-    /// Selection of different renderings which can be used by <see cref="Tree"/>.
-    /// </summary>
-    public static class TreeRendering
-    {
-        /// <summary>
-        /// Gets ASCII rendering of a tree.
-        /// </summary>
-        public static ITreeRendering Ascii { get; } = new AsciiTreeRendering();
-    }
-}