Alpha implementation of dependency property source generator.

Testing project for source generator

WpfExtended.SourceGeneration/Templates/SimpleCodeTemplate.cs

@@ -0,0 +1,18 @@
+namespace System.Extensions.Templates
+{
+    internal sealed class SimpleCodeTemplate : CodeTemplate
+    {
+        public string Code { get; set; }
+
+        public SimpleCodeTemplate WithCode(string code)
+        {
+            this.Code = code;
+            return this;
+        }
+
+        public override void Generate(CodeWriter codeWriter)
+        {
+            codeWriter.Append(this.Code);
+        }
+    }
+}