(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.
    Also add 'every' aggregate.

(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.


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.

Fabien COELHO