Strings in weak tables

[Mark Hamburg <mhamburg@...>]

While I understand the reasoning for making strings act like values with
respect to weak tables, it can be a problem when dealing with computed
strings. For example, I might want to cache SQL statements and their
compiled form for SQLite.

Two questions:

1. Is it sufficient to change iscleared in lg.c to not treat strings
specially to change the behavior?

-and-

2. Should Lua perhaps add the option of including an "s" in the mode field
to indicate that strings are weak? One issue I could see here is that it
probably then pushes for marking strings at a different point in the
processing in working with weak tables if the weakness of strings can vary
from table to table.

Mark