Add IWritable interface

SabreTools.Wrappers/IWritable.cs

@@ -0,0 +1,16 @@
+namespace SabreTools.Wrappers
+{
+    /// <summary>
+    /// Represents an item that can have its model written directly
+    /// </summary>
+    public interface IWritable
+    {
+        /// <summary>
+        /// Write to an output directory
+        /// </summary>
+        /// <param name="outputDirectory">Output directory to write to</param>
+        /// <param name="includeDebug">True to include debug data, false otherwise</param>
+        /// <returns>True if writing succeeded, false otherwise</returns>
+        public bool Write(string outputDirectory, bool includeDebug);
+    }
+}