add support for deferred updates
Merge branch 'new-throttle' into deferred-updates
Merge branch 'new-throttle' into deferred-updates
Recursive updates of computed are not prevented.
Use notifySubscribers instead of subscribe to do rate-limiting. This doesn't properly handle the deferEvaluation tests.
Fix initialization of "deferEvaluation" computed observable.
Replace notifySubscribers in the limit function instead of having extra login in the normal notifySubscribers.
Merge branch 'new-throttle-using-notifySubscribers' into deferred-updates
Make limit function private; take out "funcOptions" and use anonymous function instead; don't pass "target" to the callback.

Add tests showing behavior of multiple calls to rateLimit.
Merge branch 'new-throttle-using-notifySubscribers' into deferred-updates
Update deferred extender to work use an anonymous function.