Fix some quoting functions. In particular handle NULLs better.

Use a method to add primary key information rather than direct
manipulation of the class structures.

Break decimal out in _quote (in pg.py) and treat it as float.

Treat timestamp like date for quoting purposes.

Remove a redundant SELECT from the get method speeding it, and
insert since it calls get, up a little.

Add test for BOOL type in typecast method to pgdbTypeCache class.
(tv@beamnet.de)

Fix pgdb.py to send port as integer to lower level function
(dildog@l0pht.com)

Change pg.py to speed up some operations

Allow updates on tables with no primary keys.

D'Arcy J.M. Cain