new aggregate functions v1

Dear patchers,

please find attached a small patch for adding new aggregate functions:

(1) boolean-and and boolean-or aggregates named bool_and and bool_or.
    they correspond to standard sql every and some/any aggregates.
    they do not have the right name as there is a problem with
    the standard and the parser for some/any.

(2) bitwise integer aggregates named bit_and and bit_or for
    int2, int4, int8 and bit types. They are not standard,
    however they exist in other db (eg mysql), and I needed them
    for some other stuff.


The patch adds:

- 3 new functions for boolean aggregates in src/backed/utils/adt/bool.c,
  src/include/utils/builtins.h and src/include/catalog/pg_proc.h

- new aggregates declared in src/include/catalog/pg_proc.h and
  src/include/catalog/pg_aggregate.h

- some documentation and validation about these new aggregates.

It also updates the catalog version. It validates for me.

Have a nice day,

--
Fabien Coelho - coelho@cri.ensmp.fr