Replaced interval+take1+subscribeNext with afterDelay
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)
Make NSString properties copy
Get rid of the beforeAll block
Complete when NSUserDefaults deallocates
Test that the terminal sends an initial value
Clarify that the terminal sends a value upon subscription
Add a third slash for Xcode
Refactoring: buffer copying optimized. Formatting fixed.
Documentation added. Public header added to common headers list.
Turn -rac_willDeallocSignal into a replaying signal
Simplify the documentation