added onto the end of a query in some inappropriate situations, such
as when querying from an exists() of a single-inheritance subclass.

fixes #3582

function; the caller still passes in the "wrapper"
- move tests for wrap_callable() to be generic util tests
- changelog for pullreq github:204

"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.

which indicates to the ORM that a positive set of None should be
persisted as the value NULL, instead of omitting the column from
the INSERT statement.  This feature is used both as part of the
implementation for :ticket:`3514` as well as a standalone feature
available on any type.  fixes #3250
- add new documentation section illustrating the "how to force null"
 use case of #3250
- alter our change from #3514 so that the class-level flag is now
called "should_evaluate_none"; so that "evaluates_none" is now
a generative method.