Added image conversion parts from commonwin32.

NTwain/Interop/MESSAGE.cs

@@ -0,0 +1,34 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace NTwain.Interop
+{
+    /// <summary>
+    /// The MSG structure in Windows for TWAIN use.
+    /// </summary>
+    [StructLayout(LayoutKind.Sequential)]
+    struct MESSAGE
+    {
+        public MESSAGE(IntPtr hwnd, int message, IntPtr wParam, IntPtr lParam)
+        {
+            _hwnd = hwnd;
+            _message = (uint)message;
+            _wParam = wParam;
+            _lParam = lParam;
+            _time = 0;
+            _x = 0;
+            _y = 0;
+        }
+
+        IntPtr _hwnd;
+        uint _message;
+        IntPtr _wParam;
+        IntPtr _lParam;
+        uint _time;
+        int _x;
+        int _y;
+    }
+}