and ``__declare_last__`` accessors where these would no longer be
called on the superclass of the declarative base.
fixes #3383

applying any topological sort to tables on SQLite.  See the
changelog for details, but we now continue to sort
tables for SQLite on DROP, prohibit the sort from considering
alter, and only warn if we encounter an unresolvable cycle, in
which case, then we forego the ordering.  use_alter as always
is used to break such a cycle.
fixes #3378

consists mainly of adjusting fixtures to ensure connections are closed
explicitly.  psycopg2cffi also handles unicode bind parameter
names differently than psycopg2, and seems to possibly have a little less
control over floating point values at least in one test which is
marked as a "fail", though will see if it runs differently on linux
than osx..
- changelog for psycopg2cffi, fixes #3052

sort_tables_and_constraints function.
- The DDL generation system of :meth:`.MetaData.create_all`
and :meth:`.Metadata.drop_all` has been enhanced to in most
cases automatically handle the case of mutually dependent
foreign key constraints; the need for the
:paramref:`.ForeignKeyConstraint.use_alter` flag is greatly
reduced.  The system also works for constraints which aren't given
a name up front; only in the case of DROP is a name required for
at least one of the constraints involved in the cycle.
fixes #3282

such that it has less chance of interfering with a joinload() in the
very rare circumstance that an object points to itself; in this
scenario, the object refers to itself while loading its attributes
which can cause a mixup between loaders.   The use case of
"object points to itself" is not fully supported, but the fix also
removes some overhead so for now is part of testing.
fixes #3145

sqlalchemy/orm, sqlalchemy/event, sqlalchemy/testing

to get all flake8 passing