*   Fixed `NFData` instance for `T`; before, was shallow.
*   Added `Typeable` instances for all tuple types, and for `BVar`.
*   Added `Eq`, `Ord`, `Show`, etc. instances for `T`.
*   Added `Binary` instances for all tuple types.  Note that this does incur a
    *binary* dependency only because of the tuple types; however, this will
    hopefully be not too much of an issue because *binary* is a GHC library
    anyway.