merge 0.9.8 start
- Added a supported :meth:`.FunctionElement.alias` method to functions,
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