[SQLObject] Schema creation (in CVS)

I've implemented table creation in CVS.  The new class methods
createTable and dropTable do what you might expect.

However, to do this you have to give more information about your
columns.  The new Col module defines several subclasses for different
types of columns.  While constraints are used there, they aren't
actually checked yet.

The extra information about columns won't be required.  While it's
necessary for some features, I don't see any reason it would be required
for normal use.

  Ian