- the ordering of columns in a multi-column property now is in

- the ordering of columns in a multi-column property now is in
  reverse order of which they were added to the property. A
  typical effect of this is that the ".id" attribute on a
  joined-inheritance subclass, where both parent/child tables
  name the PK column ".id", will reference the ".id" column of
  the child table, not the parent, thus allowing join conditions
  and such to be constructed more intuitively. This is a
  behavior change for some joined-table inheritance queries.
  [ticket:1892]
- it's now an error condition to map to a join where multiple
  same-named columns from each table combine themselves
  implicitly. An explicit mention in the "properties" dictionary
  should be specified, using a list of columns, or
  column_property(*cols) with declarative. [ticket:1892]