didn't match.  use straight memoized_props here for now, add a perf test to check it

tuple is; this is accomplished via ensuring tuple() conversion on
both sides within the ``__eq__()`` method as well as
the addition of a ``__lt__()`` method. [ticket:2848]

courtesy Hajime Nakagami.

provided via the :func:`.event.remove` function.
[ticket:2268]
- reorganization of event.py module into a package; with the addition of the
docstring work as well as the new registry for removal, there's a lot more code now.
the package separates concerns and provides a top-level doc for each subsection
of functionality
- the remove feature works by providing the EventKey object which associates
the user-provided arguments to listen() with a global, weak-referencing registry.
This registry stores a collection of _ListenerCollection and _DispatchDescriptor
objects associated with each set of arguments, as well as the wrapped function
which was applied to that collection.  The EventKey can then be recreated for
a removal, all the _ListenerCollection and _DispatchDescriptor objects are located,
and the correct wrapped function is removed from each one.

when loading mapped entities.   The function overhead of applying
a per-object deferred callable to an instance at load time was
significantly higher than that of just loading the data from the row
(note that ``defer()`` is meant to reduce DB/network overhead, not
necessarily function call count); the function call overhead is now
less than that of loading data from the column in all cases.  There
is also a reduction in the number of "lazy callable" objects created
per load from N (total deferred values in the result) to 1 (total
number of deferred cols).
[ticket:2778]

actual mock objects from the mock library.  I'd like to use mock
for new tests so we might as well use it in obvious places.
- use unittest.mock in py3.3
- changelog
- add a note to README.unittests
- add tests_require in setup.py
- have tests import from sqlalchemy.testing.mock
- apply usage of mock to one of the event tests.  we can be using
this approach all over the place.

- rewrite all profiles, we'll review the diffs to see if anything is too far out

as possible

- went through examples/ and cleaned out excess list() calls