what's given so we need to use a set() here.  contains_column is not within
any performance paths

need this collection except in the extend/update uses where we
create it ad-hoc.  simplifies pickling.  Compatibility with 1.0
should be OK as ColumnColleciton uses __getstate__ in any case
and the __setstate__ contract hasn't changed.
- Fixed bug in :class:`.Table` metadata construct which appeared
around the 0.9 series where adding columns to a :class:`.Table`
that was unpickled would fail to correctly establish the
:class:`.Column` within the 'c' collection, leading to issues in
areas such as ORM configuration.   This could impact use cases such
as ``extend_existing`` and others.  fixes #3632

as subqueries in order to work around SQLite's lack of support for this
syntax, is lifted when SQLite version 3.7.16 or greater is detected.
fixes #3634
- The workaround for SQLite's unexpected delivery of column names as
``tablename.columnname`` for some kinds of queries is now disabled
when SQLite version 3.10.0 or greater is detected.
fixes #3633

create confusion for inherited classes such as BYTEA, fixes

when the construct contains non-standard sql elements such as
returning, array index operations, or dialect-specific or custom
datatypes.  a string is now returned in these cases rendering an
approximation of the construct (typically the postgresql-style
version of it) rather than raising an error. fixes #3631
- add within_group to top-level imports
- add eq_ignore_whitespace to sqlalchemy.testing imports

method, and its interaction with result-row processing, now allows
the columns passed to the method to be positionally matched with the
result columns in the statement, rather than matching on name alone.
The advantage to this includes that when linking a textual SQL statement
to an ORM or Core table model, no system of labeling or de-duping of
common column names needs to occur, which also means there's no need
to worry about how label names match to ORM columns and so-forth.  In
addition, the :class:`.ResultProxy` has been further enhanced to
map column and string keys to a row with greater precision in some
cases.  fixes #3501
- reorganize the initialization of ResultMetaData for readability
and complexity; use the name "cursor_description", define the
task of "merging" cursor_description with compiled column information
as its own function, and also define "name extraction" as a separate task.
- fully change the name we use in the "ambiguous column" error to be the
actual name that was ambiguous, modify the C ext also

for SQL fragments; we've deprecated that in 1.0 and its a good idea
to document like this for 0.9 as well.

back by using an attrgetter for the default case

This supports the use case of an application that uses the same set of
:class:`.Table` objects in many schemas, such as schema-per-user.
A new execution option
:paramref:`.Connection.execution_options.schema_translate_map` is
added. fixes #2685
- latest tox doesn't like the {posargs} in the profile rerunner