now be constructed such that the visit methods receive an indication
of the owning expression object, if any.  Any visit method that
accepts keyword arguments (e.g. ``**kw``) will in most cases
receive a keyword argument ``type_expression``, referring to the
expression object that the type is contained within.  For columns
in DDL, the dialect's compiler class may need to alter its
``get_column_specification()`` method to support this as well.
The ``UserDefinedType.get_col_spec()`` method will also receive
``type_expression`` if it provides ``**kw`` in its argument
signature.
fixes #3074

sqlalchemy/orm, sqlalchemy/event, sqlalchemy/testing

to get all flake8 passing

arguments; [ticket:2866]
- add dialect specific kwarg functionality to ForeignKeyConstraint, ForeignKey

to query from the ``rdb$relations`` view instead of the
``rdb$relation_fields`` and ``rdb$view_relations`` views.
Variants of both the old and new queries are mentioned on many
FAQ and blogs, however the new queries are taken straight from
the "Firebird FAQ" which appears to be the most official source
of info. [ticket:2898]