RACSequence addition added to NSIndexSet
Reive notes taken into account, small odds fixed
NSIndexSet sequence additions TestSpec fixed according to Notes
Failing test (under Release) for KVOing zombies
Manually control object lifetime in property subscription

This way, we can block -dealloc while we’re reading the objects, to
avoid any possible race conditions from deallocating on another thread
at the same time we start observing the object.
Skip subscription in -takeUntil: upon immediate completion
Strongify immediately upon reading
Explain why we lock the whole scope
Optimize like hell in test builds (to exercise races)
Refactoring: buffer copying optimized. Formatting fixed.
Documentation added. Public header added to common headers list.
Turn -rac_willDeallocSignal into a replaying signal
Small modifications according to review notes
Make NSIndexSet+RACSequenceAdditions public
Remove umbrella import from RACIndexSetSequence
Simplify RACIndexSetSequence with derived variables
Various style fixes
Merge pull request #1031 from ReactiveCocoa/pr/1019

NSIndexSet.rac_sequence redux
Merge branch 'master' into kvo-dealloc-race
Merge pull request #1026 from ReactiveCocoa/kvo-dealloc-race

Attempt to fix resurrection of dead objects in KVO signals