Add inverse transition functions for the bool_and and bool_or aggregates.

Note that this patch removed the sort operator on bool_and and bool_or, this may mean
that this part of the patch is rejected, but I discovered this only after I had done
must of the work for it, so I thought I would continue and get some comments on this.
Please also be aware that I have left some regression tests failing which ensure these
have a valid sort operator to remind me that this needs either fixed or reverted before
inverse transition functions are ready for PostgreSQL.