Change-Id: I8172fdcc3103ff92aa049827728484c8779af6b7

References: #4600
Change-Id: I2a62ddfe00bc562720f0eae700a497495d7a987a

The major action here is to lift and move future.Connection
and future.Engine fully into sqlalchemy.engine.base.   This
removes lots of engine concepts, including:

* autocommit
* Connection running without a transaction, autobegin
  is now present in all cases
* most "autorollback" is obsolete
* Core-level subtransactions (i.e. MarkerTransaction)
* "branched" connections, copies of connections
* execution_options() returns self, not a new connection
* old argument formats, distill_params(), simplifies calling
  scheme between engine methods
* before/after_execute() events (oriented towards compiled constructs)
  don't emit for exec_driver_sql().  before/after_cursor_execute()
  is still included for this
* old helper methods superseded by context managers, connection.transaction(),
  engine.transaction() engine.run_callable()
* ancient engine-level reflection methods has_table(), table_names()
* sqlalchemy.testing.engines.proxying_engine

References: #7257

Change-Id: Ib20ed816642d873b84221378a9ec34480e01e82c

* docs for event listen kwargs
* docs for mysql to use `listen` for changing the sql_mode`

Change-Id: I7c1678488658edda3c5baaf0f7648108e93a4be1

Added some guards against ``KeyError`` in the event system to accommodate
the case that the interpreter is shutting down at the same time
:meth:`_engine.Engine.dispose` is being called, which would cause stack
trace warnings.

Fixes: #6740
Change-Id: I2c42e9edac2371e68b39d8360494c5fddfd6cd8c

Also replace http://pypi.python.org/pypi with https://pypi.org/project

Change-Id: I84b5005c39969a82140706472989f2a30b0c7685

Fixed critical regression caused by the change in :ticket`5497` where the
connection pool "init" phase no longer occurred within mutexed isolation,
allowing other threads to proceed with the dialect uninitialized, which
could then impact the compilation of SQL statements.

This issue is essentially the same regression which was fixed many years
ago in :ticket:`2964` in dd32540dabbee0678530fb1b0868d1eb41572dca,
which was missed this time as the test suite fo
that issue only tested the pool in isolation, and assumed the
"first_connect" event would be used by the Engine.  However
:ticket:`5497` stopped using "first_connect" and no test detected
the lack of mutexing, that has been resolved here through
the addition of more tests.

This fix also identifies what is probably a bug in earlier versions
of SQLAlchemy where the "first_connect" handler would be cancelled
if the initializer failed; this is evidenced by
test_explode_in_initializer which was doing a reconnect due to
c.rollback() yet wasn't hanging.  We now solve this issue by
preventing the manufactured Connection from ever reconnecting
inside the first_connect handler.

Also remove the "_sqla_unwrap" test attribute; this is almost
not used anymore however we can use a more targeted
wrapper supplied by the testing.engines.proxying_engine
function.

See if we can also open up Oracle for "ad hoc engines" tests
now that we have better connection management logic.

Fixes: #6337
Change-Id: I4a3476625c4606f1a304dbc940d500325e8adc1a

Uses the flake8 option per-file-ignores that was introduced in a recent
version of flake8 (3.7.+) to avoid having lots of "noqa" in import
only files

Change-Id: Ib4871d63bad7e578165615df139cbf6093479201

Repaired / implemented support for primary key constraint naming
conventions that use column names/keys/etc as part of the convention. In
particular, this includes that the :class:`.PrimaryKeyConstraint` object
that's automatically associated with a :class:`.schema.Table` will update
its name as new primary key :class:`_schema.Column` objects are added to
the table and then to the constraint. Internal failure modes related to
this constraint construction process including no columns present, no name
present or blank name present are now accommodated.

Fixes: #5919
Change-Id: Ic2800b50f4a4cd5978bec48cefea0a2e198e0123

Change-Id: Ic5bb19ca8be3cb47c95a0d3315d84cb484bac47c