Hi,

I did some changes to support :dbname, :dbhost and :database in SQL code 
blocks when using postgresql engine.

Even if it was possible to specify this information using :cmdline 
parameter, I thought it was a bit cleaner to be able to provide this 
information in a way independent from the command line.

I will gladly accept any remark / comment on this patch.

Regards,
Steven Rémot