utils: add Result / Option types

Add some Rust-style Result/Option types, based on TartanLlama's
expected, optional classes.

There's std::optional of course, but we can't depend on C++17 yet.

lib/utils/mu-error.hh

@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2019 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2019-2020 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 **
 ** This program is free software; you can redistribute it and/or modify it
 ** under the terms of the GNU General Public License as published by the
@@ -129,8 +129,6 @@ private:
         std::string  what_;
 };
 
-
 } // namespace Mu
 
-
 #endif /* MU_ERROR_HH__ */