PATCH: recursive json_populate_record()

Hi.

The first attached patch implements recursive processing of nested
objects and arrays in json[b]_populate_record[set](),
json[b]_to_record[set](). See regression tests for examples.

It also fixes the following errors/inconsistencies caused by lost
quoting of string json values:

[master]=# select * from json_to_record('{"js": "a"}') as rec(js json);
ERROR: invalid input syntax for type json
DETAIL: Token "a" is invalid.
CONTEXT: JSON data, line 1: a

[master]=# select * from json_to_record('{"js": "true"}') as rec(js json);
js
------
true

[patched]=# select * from json_to_record('{"js": "a"}') as rec(js json);
js
-----
"a"

[patched]=# select * from json_to_record('{"js": "true"}') as rec(js json);
js
--------
"true"

The second patch adds assignment of correct ndims to array fields of
RECORD function result types.
Without this patch, attndims in tuple descriptors of RECORD types is
always 0 and the corresponding assertion fails in the next test:

[patched]=# select json_to_record('{"a": [1, 2, 3]}') as rec(a int[]);

Should I submit these patches to commitfest?

--
Nikita Glukhov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company