Named arguments

[gonzalobg]

Problem

C doesn't have named arguments, but Fortran and Python do.

It might make sense to explicitly state that while the argument names on C are not required or non-normative, that they are encouraged to simplify creating idiomatic wrappers over the MPI ABI from languages with named arguments like Fortran or Python.

And we might want to go as far as actually requiring these names to be used in the MPI ABI so that such wrappers can rely on this.