Add Spectre.Cli to Spectre.Console

* Renames Spectre.Cli to Spectre.Console.Cli.
* Now uses Verify with Spectre.Console.Cli tests.
* Removes some duplicate definitions.

Closes #168

examples/Cli/Delegates/Program.cs

@@ -0,0 +1,39 @@
+using System;
+using Spectre.Console.Cli;
+
+namespace Delegates
+{
+    public static partial class Program
+    {
+        public static int Main(string[] args)
+        {
+            var app = new CommandApp();
+            app.Configure(config =>
+            {
+                config.AddDelegate("foo", Foo)
+                    .WithDescription("Foos the bars");
+
+                config.AddDelegate<BarSettings>("bar", Bar)
+                    .WithDescription("Bars the foos"); ;
+            });
+
+            return app.Run(args);
+        }
+
+        private static int Foo(CommandContext context)
+        {
+            Console.WriteLine("Foo");
+            return 0;
+        }
+
+        private static int Bar(CommandContext context, BarSettings settings)
+        {
+            for (var index = 0; index < settings.Count; index++)
+            {
+                Console.WriteLine("Bar");
+            }
+
+            return 0;
+        }
+    }
+}