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
Merge remote-tracking branch 'origin/master' into mac-static-library
Build EXTRuntimeExtensions into static library too