the import structure of many core modules.
``sqlalchemy.schema`` and ``sqlalchemy.types``
remain in the top-level package, but are now just lists of names
that pull from within ``sqlalchemy.sql``.  Their implementations
are now broken out among ``sqlalchemy.sql.type_api``, ``sqlalchemy.sql.sqltypes``,
``sqlalchemy.sql.schema`` and ``sqlalchemy.sql.ddl``, the last of which was
moved from ``sqlalchemy.engine``.  ``sqlalchemy.sql.expression`` is also
a namespace now which pulls implementations mostly from ``sqlalchemy.sql.elements``,
``sqlalchemy.sql.selectable``, and ``sqlalchemy.sql.dml``.
Most of the "factory" functions
used to create SQL expression objects have been moved to classmethods
or constructors, which are exposed in ``sqlalchemy.sql.expression``
using a programmatic system.  Care has been taken such that all the
original import namespaces remain intact and there should be no impact
on any existing applications.   The rationale here was to break out these
very large modules into smaller ones, provide more manageable lists
of function names, to greatly reduce "import cycles" and clarify the
up-front importing of names, and to remove the need for redundant
functions and documentation throughout the expression package.

what is strange is how it only occurred in some very specific places under very
particular conditions, perhaps it has to do with whether or not this cursor gets
gc'ed or not.

ideas in general:
  - pypy2.1 w/ sqlite3 is the first DBAPI we're seeing returning
    unicode in cursor.description without being py3k.  add a new on-connect
    check for this, if we get back a u"", just don't do description decoding,
    should be OK for now.
  - the set tests in test_collection were assuming the two sets would be ordered
    the same when it tested pop(), can't really assume that.
  - test_serializer gets worse and worse, pickle is just not really viable here,
    ding out pypy
  - pypy2.1b2 seems to allow cursor.lastrowid to work (or we changed something?)
  - pool._threadconns.current() is a weakref, it can be None
  - another one of those logging.handlers imports

make sure that the DBAPI connection passed to the reset-on-return events/dialect hooks
is also a "fairy", so that dictionaries like "info" are available.  [ticket:2770]
- rework the execution_options system so that the dialect is given the job of making
any immediate adjustments based on a set event.  move the "isolation level" logic to use
this new system.   Also work things out so that even engine-level execution options
can be used for things like isolation level; the dialect attaches a connect-event
handler in this case to handle the task.
- to support this new system as well as further extensibiltiy of execution options
add events engine_connect(), set_connection_execution_options(), set_engine_execution_options()

Conflicts:
	test/profiles.txt
	test/sql/test_selectable.py

workaround

as possible