string.bytes

[Dirk Laurie <dirk.laurie@...>]

By analogy to the function utf8.codes, it would be nice to have a
function string.bytes so that the construction

     for p, c in string.bytes(s) do body end

will iterate over all bytes in string s, with p being the position.
This is surprisingly clumsy in pure Lua, unless I am missing a trick.
Of course, if the string is pure ASCII, utf8.codes will do the trick.