engine_connect event, allowing easy detection of disconnects
and full invalidation of the pool

for UPDATE statements in the ORM (e.g. :ref:`feature_updatemany`)
would break on Postgresql and other RETURNING backends
when using server-side version generation
schemes, as the server side value is retrieved via RETURNING which
is not supported with executemany.
fixes #3556

:class:`.AssociationProxy` constructor, to suit the
:attr:`.AssociationProxy.info` accessor that was added in
:ticket:`2971`.  This is possible because :class:`.AssociationProxy`
is constructed explicitly, unlike a hybrid which is constructed
implicitly via the decorator syntax.
fixes #3551

"auto" now so True can indicate the dialect would support this

"auto increment" column has been changed, such that autoincrement
is no longer implicitly enabled for a :class:`.Table` that has a
composite primary key.  In order to accommodate being able to enable
autoincrement for a composite PK member column while at the same time
maintaining SQLAlchemy's long standing behavior of enabling
implicit autoincrement for a single integer primary key, a third
state has been added to the :paramref:`.Column.autoincrement` parameter
``"auto"``, which is now the default. fixes #3216
- The MySQL dialect no longer generates an extra "KEY" directive when
generating CREATE TABLE DDL for a table using InnoDB with a
composite primary key with AUTO_INCREMENT on a column that isn't the
first column;  to overcome InnoDB's limitation here, the PRIMARY KEY
constraint is now generated with the AUTO_INCREMENT column placed
first in the list of columns.

symbols with names quoted to force all-lower-case would not be
identified properly in reflection queries.  The :class:`.quoted_name`
construct is now applied to incoming symbol names that detect as
forced into all-lower-case within the "name normalize" process.
fixes #3548

may be construed as the Python "and" keyword
- add notes to ORM tutorial for beginners that Python "and" keyword
is not to be used
fixes #3545