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/Emojis/Program.cs

@@ -0,0 +1,24 @@
+using Spectre.Console;
+
+namespace EmojiExample
+{
+    public static class Program
+    {
+        public static void Main(string[] args)
+        {
+            // Show a known emoji
+            RenderEmoji();
+
+            // Show a remapped emoji
+            Emoji.Remap("globe_showing_europe_africa", Emoji.Known.GrinningFaceWithSmilingEyes);
+            RenderEmoji();
+        }
+
+        private static void RenderEmoji()
+        {
+            AnsiConsole.Render(
+                new Panel("[yellow]Hello :globe_showing_europe_africa:![/]")
+                    .RoundedBorder());
+        }
+    }
+}