Use explicit Optional<T> type for OptionalCFrame.

DataTypes/Optional.cs

@@ -0,0 +1,35 @@
+namespace RobloxFiles.DataTypes
+{
+    // Optional represents a value that can be explicitly
+    // marked as an optional variant to a specified type.
+    // In practice this is used for OptionalCFrame.
+
+    public struct Optional<T>
+    {
+        public T Value;
+        public bool HasValue => (Value != null);
+
+        public Optional(T value)
+        {
+            Value = value;
+        }
+
+        public override string ToString()
+        {
+            return Value?.ToString() ?? "null";
+        }
+
+        public static implicit operator T(Optional<T> optional)
+        {
+            if (optional.HasValue)
+                return optional.Value;
+
+            return default(T);
+        }
+
+        public static implicit operator Optional<T>(T value)
+        {
+            return new Optional<T>(value);
+        }
+    }
+}