pgsql: New json functions.

New json functions.

json_build_array() and json_build_object allow for the construction of
arbitrarily complex json trees. json_object() turns a one or two
dimensional array, or two separate arrays, into a json_object of
name/value pairs, similarly to the hstore() function.
json_object_agg() aggregates its two arguments into a single json object
as name value pairs.

Catalog version bumped.

Andrew Dunstan, reviewed by Marko Tiikkaja.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/105639900bf83fd3e3eb5b49f49b4d74d6347b9b

Modified Files
--------------
doc/src/sgml/func.sgml | 158 ++++++++++
src/backend/utils/adt/json.c | 577 ++++++++++++++++++++++++++++++++--
src/backend/utils/adt/jsonfuncs.c | 176 ++++++++---
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_aggregate.h | 1 +
src/include/catalog/pg_proc.h | 22 ++
src/include/utils/json.h | 13 +
src/test/regress/expected/json.out | 126 ++++++++
src/test/regress/expected/json_1.out | 126 ++++++++
src/test/regress/sql/json.sql | 87 +++++
10 files changed, 1219 insertions(+), 69 deletions(-)