become an externally usable package but still remains within the main sqlalchemy parent package.
in this system, we use kind of an ugly hack to get the noseplugin imported outside of the
"sqlalchemy" package, while still making it available within sqlalchemy for usage by
third party libraries.

- Added "map_to()" method to SqlSoup, which is a "master"
method which accepts explicit arguments for each aspect of
the selectable and mapping, including a base class per
mapping. [ticket:1975]

- Mapped selectables used with the map(), with_labels(),
join() methods no longer put the given argument into the
internal "cache" dictionary.  Particularly since the
join() and select() objects are created in the method
itself this was pretty much a pure memory leaking behavior.

- Importing testenv has no side effects- explicit functions provide similar behavior to the old immediate behavior of testbase
- testing.db has the configured db
- Fixed up the perf/* scripts

http://pyinsci.blogspot.com/2007/07/fastest-python-database-interface.html