pgsql: Add several generator functions for jsonb that exist for json.

Add several generator functions for jsonb that exist for json.

The functions are:
    to_jsonb()
    jsonb_object()
    jsonb_build_object()
    jsonb_build_array()
    jsonb_agg()
    jsonb_object_agg()

Also along the way some better logic is implemented in
json_categorize_type() to match that in the newly implemented
jsonb_categorize_type().

Andrew Dunstan, reviewed by Pavel Stehule and Alvaro Herrera.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/7e354ab9fe9e7c3b0a7a40f226c76bd5cf6438d0

Modified Files
--------------
doc/src/sgml/func.sgml                |   97 ++-
src/backend/utils/adt/json.c          |   44 +-
src/backend/utils/adt/jsonb.c         | 1396 +++++++++++++++++++++++++++++++++
src/backend/utils/adt/jsonb_util.c    |    2 +-
src/include/catalog/catversion.h      |    2 +-
src/include/catalog/pg_aggregate.h    |    4 +
src/include/catalog/pg_proc.h         |   26 +
src/include/utils/jsonb.h             |   16 +
src/test/regress/expected/jsonb.out   |  173 ++++
src/test/regress/expected/jsonb_1.out |  173 ++++
src/test/regress/sql/jsonb.sql        |  115 +++
11 files changed, 2003 insertions(+), 45 deletions(-)