Split Missfile with no other updates

SabreTools.DatFiles/Formats/Missfile.Reader.cs

@@ -0,0 +1,17 @@
+using System;
+
+namespace SabreTools.DatFiles.Formats
+{
+    /// <summary>
+    /// Represents parsing a Missfile
+    /// </summary>
+    internal partial class Missfile : DatFile
+    {
+        /// <inheritdoc/>
+        /// <remarks>There is no consistent way to parse a missfile</remarks>
+        public override void ParseFile(string filename, int indexId, bool keep, bool statsOnly = false, bool throwOnError = false)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}