since they've apparently added something for it

to be using getattr

unfortunately Sphinx refuses to work correctly for the columns
attribute so we just add a lame message to contains_column().

simple but unusual system allows for a dramatic savings in Python
overhead for the construction and processing of orm :class:`.Query`
objects, from query construction up through rendering of a string
SQL statement.
fixes #3054

:attr:`.Query.column_descriptions`.  This refers to the primary ORM
mapped class or aliased class that is referred to by the expression.
Compared to the existing entry for ``"type"``, it will always be
a mapped entity, even if extracted from a column expression, or
None if the given expression is a pure core expression.
references #3320

DROP TYPE instruction when a plain ``table.drop()`` is called,
assuming the object is not associated directly with a
:class:`.MetaData` object.   In order to accomodate the use case of
an enumerated type shared between multiple tables, the type should
be associated directly with the :class:`.MetaData` object; in this
case the type will only be created at the metadata level, or if
created directly.  The rules for create/drop of
Postgresql enumerated types have been highly reworked in general.
fixes #3319