Wraptor

* Throttle now supports signaling whether or not it ran, rather than
returning the wrapped function's return value. Contributed by evictor

* Added exception_catcher decorator

* Throttle now supports being attached to an instance method

* Fixed a small bug in memoize (only when using
instance_method=True)

* Memoize now supports being attached to an instance method
* Added timer context manager, to help time various blocks of code

* Minor change to class declarations. Enforce new style python classes.