Added links to previous discussions on this matter amongst the team.

Attempted to make it clear, however, that the prior discussions were
really in a different context, namely when we were trying to resolve
the question "does \xXX denote a code *unit* or a code *point*."

This RFC is proposing a way to side-step that question entirely, at
least in the context of string literals.  (I'll leave aside the
question of if we are really side-stepping it, given our treatment of
byte-string literals.)