Alter string format used for integer and OID lists in stored rules.

Alter string format used for integer and OID lists in stored rules.
This simplifies and speeds up the reader by letting it get the representation
right the first time, rather than correcting it after-the-fact.  Also,
after int and OID lists become separate node types per Neil's pending
patch, this will let us treat these lists as just plain Nodes instead
of requiring separate read/write macros the way we have now.