Lookup Mono SDK path on Windows registry.

src/Core/Toolchains/ManagedToolchain.cs

@@ -2,15 +2,42 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using Microsoft.Win32;
 
 namespace CppSharp
 {
     public static class ManagedToolchain
     {
-        public static string FindMonoPath()
+        public static string ReadMonoPathFromWindowsRegistry(bool prefer64bits = false)
+        {
+            using (var baseKey = RegistryKey.OpenBaseKey (RegistryHive.LocalMachine,
+                prefer64bits ? RegistryView.Registry64 : RegistryView.Registry32))
+            {
+                if (baseKey == null)
+                    return null;
+
+                using (var subKey = baseKey.OpenSubKey (@"SOFTWARE\Mono"))
+                {
+                    if (subKey == null)
+                        return null;
+
+                    return (string)subKey.GetValue ("SdkInstallRoot", "");
+                }
+            }
+        }
+
+        public static string FindMonoPath(bool prefer64bits = false)
         {
             if (Platform.IsWindows)
+            {
+                // Try to lookup the Mono SDK path from registry.
+                string path = ReadMonoPathFromWindowsRegistry(prefer64bits);
+                if (!string.IsNullOrEmpty(path))
+                   return path;
+
+                // If that fails, then lets try a default location.
                 return @"C:\Program Files (x86)\Mono";
+            }
             else if (Platform.IsMacOS)
                 return "/Library/Frameworks/Mono.framework/Versions/Current";
             else