a rollback() before re-raising, so that the stack
trace is preserved from sys.exc_info() before entering
the rollback.  This so that the traceback is preserved
when using coroutine frameworks which may have switched
contexts before the rollback function returns.
[ticket:2703]

- get the assumption of "1" for "first sequence item" to be dialect configured

for cursor.lastrowid would not function correctly
in conjunction with :attr:`.ResultProxy.inserted_primary_key`.

through ``encode()``, as this is not valid on Python 3, and prevented
statements from functioning correctly on Python 3.  We now
encode only if ``supports_unicode_binds`` is False, which is not
the case for cx_oracle when at least version 5 of cx_oracle is used.

an INSERT that's used in executemany() as opposed to one which has a VALUES
clause with multiple entries.

Some databases support this syntax for inserts:

INSERT INTO table (id, name) VALUES
('v1', 'v2'),
('v3', 'v4');

which greatly increases INSERT speed.

It is now possible to pass a list of lists/tuples/dictionaries as
the values param to the Insert construct. We convert it to a flat
dictionary so we can continue using bind params. The above query
will be converted to:

INSERT INTO table (id, name) VALUES
(:id, :name),
(:id0, :name0);

Currently only supported on postgresql, mysql and sqlite.

whereas the other do_rollback_twophase(), savepoint etc. work with
:class:`.Connection`.  the context on these are different as twophase/savepoint
are available at the :class:`.Connection` level, whereas commit/rollback are needed
at a lower level as well.  Rename the argument to "dbapi_connection" when the conneciton
is in fact the DBAPI interface.
- start thinking about being able to track "autocommit" vs. "commit", but not sure
we have a need for this yet.
- have Pool call out to a Dialect for all rollback/commit/close operations now.  Pool
no longer calls DBAPI methods directly.  May use this for a workaround for [ticket:2611]
- add a new Pool event reset() to allow the pool's reset of the connection to be intercepted.
- remove methods in Informix dialect which appear to be hardcoding some isolation
settings on new Transaction only; the isolation API should be implemented for Informix.
also removed "flag" for transaction commit/rollback being not available; this should
be based on server/DBAPI version and we will need someone with test access in order
to help determine how this should work