Write protected tables

[Mark Hamburg <mhamburg@...>]

For a variety of purposes, it would be useful to force writes to some tables
through __newindex or a new metamethod even if the key was already present.
Yes, I can do this by putting a proxy table in the way and hiding all of the
keys, but this requires two tables instead of one, impacts read performance,
and has ripple effects to other routines like next, foreach, etc..

Is luaV_settable the only routine I would need to change in order to
implement this?

Mark