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/Console/Columns/Program.cs

@@ -0,0 +1,31 @@
+using System.Collections.Generic;
+using Spectre.Console;
+
+namespace ColumnsExample
+{
+    public static class Program
+    {
+        public static void Main()
+        {
+            var cards = new List<Panel>();
+            foreach(var user in User.LoadUsers())
+            {
+                cards.Add(
+                    new Panel(GetCardContent(user))
+                        .Header($"{user.Country}")
+                        .RoundedBorder().Expand());
+            }
+
+            // Render all cards in columns
+            AnsiConsole.Render(new Columns(cards));
+        }
+
+        private static string GetCardContent(User user)
+        {
+            var name = $"{user.FirstName} {user.LastName}";
+            var city = $"{user.City}";
+
+            return $"[b]{name}[/]\n[yellow]{city}[/]";
+        }
+    }
+}