Replaced the inheriting constructor with a forwarding constructor.
Removed the template constructors that are covered by the forwarding constructor.
Added std::forward() to make_tuple.
Added conversion constructor.
Moved msgpack::type::tuple to
include/msgpack/v1/adaptor/detail/cpp11_msgpack_tuple_decl.hpp from
include/msgpack/v1/adaptor/detail/cpp11_msgpack_tuple.hpp.
msgpack::type::tuple_cat requires the class template tuple definition.