Remove RACExtensions from test targets
Add RACExtensions to product targets
Make RACExtension headers public
mv RACExtensions/* ReactiveCocoaFramework/ReactiveCocoa

Also, in Xcode project land:

    mv RACExtensions/* "Foundation Support"
    rm RACExtensions
Sort Foundation Support group
Add ex-RACExtensions to ReactiveCocoa.h
Header Shit Work
Merge pull request #817 from ReactiveCocoa/graduate-racextensions

Graduate RACExtensions
Add ReactiveCocoa-Mac static library target
Add ReactiveCocoa-Mac to script/cibuild
Add all headers to ReactiveCocoa-Mac

Also fix a couple that were erroneously in/not in ReactiveCocoa and ReactiveCocoa-iOS
Document -initially: order
Generalized -distinctUntilChanged to RACStream

-distinctUntilChanged doesn't actually use any kit which is specific to
signals, as opposed to other streams. Seems to make sense to just move
it to RACStream, then.
Add -initially: example and try to be less word jumbly
Slight rewording of example comment
Now with 0.1% better succinctness
Merge pull request #823 from jonsterling/generalize-distinctUntilChanged

Generalized -distinctUntilChanged to RACStream
Use two -initially:'s in example
Merge pull request #822 from ReactiveCocoa/document-initially-order

Document -initially: order
Add DTrace probes for compound disposable growth