Added support for marshaling .NET strings.

binder/Generators/C/CMarshal.cs

@@ -17,6 +17,31 @@ namespace MonoManagedToNative.Generators
         public CMarshalManagedToNative(MarshalContext marshalContext)
             : base(marshalContext)
         {
+        }
+
+        bool HandleSpecialCILType(CILType cilType)
+        {
+            var type = cilType.Type;
+
+            if (type == typeof(string))
+            {
+                var stringId = CGenerator.GenId("string");
+                Context.SupportBefore.WriteLine("char* {0} = mono_string_to_utf8(" +
+                    "(MonoString*) {1});", stringId, Context.ArgName);
+
+                Context.Return.Write("{0}", stringId);
+                return true;
+            }
+
+            return false;
+        }
+
+        public override bool VisitCILType(CILType type, TypeQualifiers quals)
+        {
+            if (HandleSpecialCILType(type))
+                return true;
+
+            return base.VisitCILType(type, quals);
         }
 
         public override bool VisitBuiltinType(BuiltinType builtin,