PostgresSQL DLR support

Hi,

attached is a patch that adds postgresql dlr support to kannel. it's pretty 
much untested, so please test and comment. it's modeled much after the mysql 
implementation.

New files:

N doc/examples/dlr-pgsql.conf
N gw/dlr_pgsql.c
N gwlib/dbpool_pgsql.c

Modified files:

M configure.in
M gw-config.h.in
M gw/dlr.c
M gw/dlr_p.h
M gwlib/cfg.def
M gwlib/dbpool.c
M gwlib/dbpool.h

test and comments welcome.

- Martin -