Update emoji support

* Add constants for emojis
* Move emoji shortcode rendering to Markup
* Add documentation
* Add example
* Add tests

docs/src/Modules/ReadEmbedded.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading.Tasks;
+using Statiq.Common;
+
+namespace Docs.Modules
+{
+    public sealed class ReadEmbedded : Module
+    {
+        private readonly System.Reflection.Assembly _assembly;
+        private readonly string _resource;
+
+        public ReadEmbedded(System.Reflection.Assembly assembly, string resource)
+        {
+            _assembly = assembly ?? throw new ArgumentNullException(nameof(assembly));
+            _resource = resource ?? throw new ArgumentNullException(nameof(resource));
+        }
+
+        protected override Task<IEnumerable<IDocument>> ExecuteContextAsync(IExecutionContext context)
+        {
+            return Task.FromResult((IEnumerable<IDocument>)new[]
+            {
+                context.CreateDocument(ReadResource()),
+            });
+        }
+
+        private Stream ReadResource()
+        {
+            var resourceName = _resource.Replace("/", ".");
+
+            var stream = _assembly.GetManifestResourceStream(resourceName);
+            if (stream == null)
+            {
+                throw new InvalidOperationException("Could not load manifest resource stream.");
+            }
+
+            return stream;
+        }
+    }
+}