new aggregate functions v2

Dear patchers,

please find attached my second patch submission for adding
new aggregate functions:

(1) boolean-and and boolean-or aggregates named bool_and and bool_or.
they should 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. Tom also think that
the standard name is misleading because NULL are ignored.

(2) bitwise integer aggregates named bit_and and bit_or for
int2, int4, int8 and bit types. They are not standard, but I find
them useful. I needed them once, and I'm not the first one to look for
them.

The patches adds:

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

- the 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(at)cri(dot)ensmp(dot)fr