pgsql: Add ALTER TYPE ... ADD/DROP/ALTER/RENAME ATTRIBUTE

Add ALTER TYPE ... ADD/DROP/ALTER/RENAME ATTRIBUTE

Like with tables, this also requires allowing the existence of
composite types with zero attributes.

reviewed by KaiGai Kohei

Branch
------
master

Details
-------
http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=e440e12c562432a2a695b8054964fb34e3bd823e

Modified Files
--------------
doc/src/sgml/ref/alter_type.sgml | 130 ++++++++++++++-
doc/src/sgml/ref/create_type.sgml | 22 ++-
doc/src/sgml/ref/drop_type.sgml | 4 +-
src/backend/commands/alter.c | 2 +
src/backend/commands/tablecmds.c | 257 +++++++++++++++++++----------
src/backend/commands/typecmds.c | 5 -
src/backend/parser/gram.y | 165 +++++++++++++++----
src/backend/parser/parse_utilcmd.c | 3 +
src/backend/tcop/utility.c | 4 +
src/bin/pg_dump/pg_dump.c | 12 +-
src/bin/psql/tab-complete.c | 34 ++++-
src/include/nodes/parsenodes.h | 1 +
src/include/parser/kwlist.h | 1 +
src/test/regress/expected/alter_table.out | 89 ++++++++++-
src/test/regress/sql/alter_table.sql | 55 ++++++
15 files changed, 636 insertions(+), 148 deletions(-)