Allow computed evaluator code to get info about computed state (initial evaluation and current dependency count). Update checked and if/ifnot/with bindings to take advantage of these.
Export ko.computedContext and add tests.
Don't export computed object in ko.computedContext.
Merge pull request #627 from knockout/627-computed-context

Provide access to dependency count within computed function
New spec showing deferEvaluation computed sometimes take dependencies after disposed
dependentObservable will no longer evaluate if it has been disposed
Prevent a computed from taking dependencies if it's disposed within the evaluator.
Minor style tweaks
Merge pull request #1209 from knockout/1209-prevent-disposed-computed-from-taking-dependencies

evaluating a disposed deferred dependentObservable causes it to take dependencies