little patch for "Detect serial columns from pg_depend" and bugfix

Hi,

Please find the attachments.

pgColumn.patch:

Detect serial columns from pg_depend, not column default (observe deviating
   serial name)

pgSequence.patch:

bugfix, in SQL pane of the sequence, the script is

CREATE SEQUENCE xxx
   ...;
ALTER TABLE ...

Regards,

Quan Zongliang