sqlalchemy/orm, sqlalchemy/event, sqlalchemy/testing

Conflicts:
	lib/sqlalchemy/dialects/mssql/base.py
	lib/sqlalchemy/dialects/mysql/base.py
	lib/sqlalchemy/dialects/mysql/mysqldb.py
	lib/sqlalchemy/dialects/oracle/base.py
	lib/sqlalchemy/dialects/sybase/base.py
	lib/sqlalchemy/orm/attributes.py
	lib/sqlalchemy/orm/evaluator.py
	lib/sqlalchemy/orm/identity.py
	lib/sqlalchemy/orm/instrumentation.py
	lib/sqlalchemy/orm/loading.py
	lib/sqlalchemy/orm/mapper.py
	lib/sqlalchemy/orm/session.py
	lib/sqlalchemy/orm/sync.py
	lib/sqlalchemy/sql/compiler.py
	lib/sqlalchemy/sql/selectable.py
	lib/sqlalchemy/testing/requirements.py
	lib/sqlalchemy/testing/suite/test_select.py

  to get all flake8 passing

form of a some expressions when referring to the ``.c`` collection
on a ``select()`` construct, but the ``str()`` form isn't available
since the element relies on dialect-specific compilation constructs,
notably the ``__getitem__()`` operator as used with a Postgresql
``ARRAY`` element.  The fix also adds a new exception class
:class:`.UnsupportedCompilationError` which is raised in those cases
where a compiler is asked to compile something it doesn't know
how to.  Also in 0.8.3.
[ticket:2780]

like to improve upon query.statement needing to do this