pgsql: PL/Python custom SPI exceptions

PL/Python custom SPI exceptions

This provides a separate exception class for each error code that the
backend defines, as well as the ability to get the SQLSTATE from the
exception object.

Jan Urbański, reviewed by Steve Singer

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/474a42473adf9b18417242f1fc0691a857ec578b

Modified Files
--------------
doc/src/sgml/plpython.sgml                         |   49 +++++++-
src/pl/plpython/.gitignore                         |    1 +
src/pl/plpython/Makefile                           |   12 ++-
src/pl/plpython/expected/plpython_error.out        |   44 ++++++-
src/pl/plpython/expected/plpython_error_0.out      |   44 ++++++-
.../plpython/expected/plpython_subtransaction.out  |   10 +-
.../expected/plpython_subtransaction_0.out         |    2 +-
src/pl/plpython/expected/plpython_test.out         |    6 +-
src/pl/plpython/generate-spiexceptions.pl          |   44 +++++++
src/pl/plpython/plpython.c                         |  129 ++++++++++++++++++--
src/pl/plpython/sql/plpython_error.sql             |   21 +++
src/tools/msvc/Solution.pm                         |    6 +
12 files changed, 342 insertions(+), 26 deletions(-)