the schema target of a :class:`.ForeignKey` will not be changed unless
that schema matches that of the parent table.  That is, if
a table "schema_a.user" has a foreign key to "schema_b.order.id",
the "schema_b" target will be maintained whether or not the
"schema" argument is passed to :meth:`.Table.tometadata`.  However
if a table "schema_a.user" refers to "schema_a.order.id", the presence
of "schema_a" will be updated on both the parent and referred tables.
This is a behavioral change hence isn't likely to be backported to
0.8; it is assumed that the previous behavior is pretty buggy
however and that it's unlikely anyone was relying upon it.

Additionally, a new parameter has been added
:paramref:`.Table.tometadata.referred_schema_fn`.  This refers to a
callable function which will be used to determine the new referred
schema for any :class:`.ForeignKeyConstraint` encountered in the
tometadata operation.  This callable can be used to revert to the
previous behavior or to customize how referred schemas are treated
on a per-constraint basis.  [ticket:2913]

- rework the tests in test.sql.test_metadata, all the "tometadata" tests
now under new class ToMetaDataTest

applied to :class:`.Constraint` and :class:`.Index` objects.  Based
on a recipe in the wiki, the new feature uses schema-events to set up
names as various schema objects are associated with each other.  The
events then expose a configuration system through a new argument
:paramref:`.MetaData.naming_convention`.  This system allows production
of both simple and custom naming schemes for constraints and indexes
on a per-:class:`.MetaData` basis.  [ticket:2923]

commit 7e65e52c086652de3dd3303c723f98f09af54db8
Author: Mike Bayer <mike_mp@zzzcomputing.com>
Date:   Sat Feb 1 15:09:04 2014 -0500

    - first pass at new naming approach

reflection now updates the PKC in place.
- support the use case of the empty PrimaryKeyConstraint in order to specify
constraint options; the columns marked as primary_key=True will now be gathered
into the columns collection, rather than being ignored. [ticket:2910]
- add validation such that column specification should only take place
in the PrimaryKeyConstraint directly, or by using primary_key=True flags;
if both are present, they have to match exactly, otherwise the condition is
assumed to be ambiguous, and a warning is emitted; the old behavior of
using the PKC columns only is maintained.

now represents exactly the kwargs that were passed, and not the defaults.
the defaults are still in dialect_options.  This allows repr() schemes such as that
of alembic to not need to look through and compare for defaults.

- clean up some shenanigans in reflection

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

column argument.   If not a string, it checks that the object is
at least a :class:`.ColumnClause`, or an object that resolves to one,
and that the ``.table`` attribute, if present, refers to a
:class:`.TableClause` or subclass, and not something like an
:class:`.Alias`.  Otherwise, a :class:`.ArgumentError` is raised.
[ticket:2883]

all :attr:`.SchemaItem.info` dictionaries from all :class:`.SchemaItem`
objects within the structure including columns, constraints,
foreign keys, etc.   As these dictionaries
are copies, they are independent of the original dictionary.
Previously, only the ``.info`` dictionary of :class:`.Column` was transferred
within this operation, and it was only linked in place, not copied.
[ticket:2716]

if it was generated from a :class:`.Column` that didn't specify ``unique``
(where it defaults to ``None``).  The flag will now always be ``True`` or
``False``. [ticket:2825]

events are called, so that attachment events can be used to dynamically
generate a name for the index based on the parent table and/or
columns. [ticket:2835]