Explicitly defaulted move assignment operator is implicitly deleted #478

chaiscript/dispatchkit/../language/chaiscript_common.hpp:731:25: warning: explicitly defaulted move assignment operator is implicitly deleted [-Wdefaulted-function-deleted]
        Stack_Push_Pop& operator=(Stack_Push_Pop &&) = default;
                        ^
chaiscript/dispatchkit/../language/chaiscript_common.hpp:748:53: note: move assignment operator of 'Stack_Push_Pop' is implicitly deleted because field 'm_ds' is of reference type 'const chaiscript::detail::Dispatch_State &'
          const chaiscript::detail::Dispatch_State &m_ds;