Dot calls / broadcasts for strings

The issue is that what one wants is what our strings do: indexing by code units and getting characters. My inclination is that there should be codeunits(str), chars(str) and graphemes(str) and they should all be indexed by code unit, but maybe wrapped in a StringIndex type that you either can’t just do bare arithmetic with or that remembers the string the index is into and does the right advancing when you do arithmetic with it.