- logging is now implemented via standard python "logging" module.

- logging is now implemented via standard python "logging" module.
"echo" keyword parameters are still functional but set/unset
log levels for their respective classes/instances.  all logging
can be controlled directly through the Python API by setting
INFO and DEBUG levels for loggers in the "sqlalchemy" namespace.
class-level logging is under "sqlalchemy.<module>.<classname>",
instance-level logging under "sqlalchemy.<module>.<classname>.<hexid>".
Test suite includes "--log-info" and "--log-debug" arguments
which work independently of --verbose/--quiet.  Logging added
to orm to allow tracking of mapper configurations, row iteration
fixes [ticket:229] [ticket:79]