pgsql: Extend format() to handle field width and left/right alignment.

Extend format() to handle field width and left/right alignment.

This change adds some more standard sprintf() functionality to format().

Pavel Stehule, reviewed by Dean Rasheed and Kyotaro Horiguchi

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/73e7025bd8eed941a068f0a7a71e02dca8d38d1c

Modified Files
--------------
doc/src/sgml/func.sgml | 222 +++++++++++++++++++-
src/backend/utils/adt/varlena.c | 395 ++++++++++++++++++++++++++++--------
src/test/regress/expected/text.out | 115 ++++++++++-
src/test/regress/sql/text.sql | 21 ++-
4 files changed, 656 insertions(+), 97 deletions(-)