e.g. the ``func`` construct.  Previously, behavior for this method
was undefined.  The current behavior mimics that of pre-0.9.4,
which is that the function is turned into a single-column FROM
clause with the given alias name, where the column itself is
anonymously named.
fixes #3137

sqlalchemy/orm, sqlalchemy/event, sqlalchemy/testing

to get all flake8 passing

Removed ungrammatical apostrophes from documentation, replacing
"it's" with "its" where appropriate (but in a few cases with "it is"
when that read better).

While doing that, I also fixed a couple of minor typos etc.
as I noticed them.

into the names used by standard functions in :mod:`sqlalchemy.sql.functions`,
such as ``func.coalesce()`` and ``func.max()``.  Using these functions
in ORM attributes and thus producing annotated versions of them could
corrupt the actual function name rendered in the SQL. [ticket:2927]