- Added an informative error message when

 - Added an informative error message when
    ForeignKeyConstraint refers to a column name in
    the parent that is not found.  Also in 0.6.9.
- add tests for [ticket:2226], as if we hit each @declared_attr
directly with obj.__get__(obj, name) instead of using
getattr(cls, name).  Basic inheritance mechanics are improperly
used in this case, so 2226 is invalid.