- Fixed 0.9 regression where the new sortable support for :class:`.RowProxy`

- Fixed 0.9 regression where the new sortable support for :class:`.RowProxy`
would lead to ``TypeError`` when compared to non-tuple types as it attempted
to apply tuple() to the "other" object unconditionally.  The
full range of Python comparison operators have now been implemented on
:class:`.RowProxy`, using an approach that guarantees a comparison
system that is equivalent to that of a tuple, and the "other" object
is only coerced if it's an instance of RowProxy. [ticket:2924]