[SQLObject] change to Col.py

[Bud P. B. <bu...@si...>]

Ian, 

I double checked the patches I sent and found that you didn't apply
one of my fixes in CVS:

Col.py, in _extraSQL:  instead of 

  if self.unique or self.alternateID:
    result.append('UNIQUE')

it would be better to state:
    
  if self.unique or self.alternateID:
    result.append('UNIQUE')
    result.append('NOT NULL')

At least in my understanding of PostgreSQL, UNIQUE does not seem to
imply NOT NULL.  

--b