v4.0-alpha.4

This release is meant for use with Xcode 7.1.x and Swift 2.1.

🚧 Remember, RAC 4 is alpha software! 🚧

Expect breaking changes in subsequent alpha releases.
See the CHANGELOG to learn more about the major changes between ReactiveCocoa versions 3 and 4.

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New features:

• Moved flatMapError to Signal (#2531 thanks @NachoSoto and @neilpa for the review!)
• Using fatalError instead of assert(false) (#2534 thanks @NachoSoto and @neilpa for the review!)
• [breaking change] Changed toRACSignal from free function to protocol extension on SignalType/SignalProducerType (#2544 thanks @NachoSoto and @neilpa for the review!)
• Added Signal.merge(signals: [Signal<T, E>]) (#2526 thanks @NachoSoto and @JaviSoto, @neilpa for the review!)
• Moved on operator to Signal (#2572 thanks to @NachoSoto and @neilpa, @jspahrsummers for the review!)
• Added new skipUntil operator (#2576 thanks to @cesteban and @NachoSoto for the review!)

Improvements

• Don't sign framework for simulators (#2520 thanks @gfontenot and @neilpa for the review!)
• Changed some class methods/properties to static (#2547 thanks @NachoSoto and @ikesyo for the review!)
• Updated Result to 1.0 (#2573 thanks to @gfontenot!)
• New logo! (#2574 thanks to @kaishin!)
• Optimized BufferState.addValue (#2580 thanks to @Adlai-Holler and @NachoSoto for the review!)
• Various code improvements to Bag (#2577 thanks @NachoSoto and @mdiep for the review!)

Bug fixes

• Changed @import to #import for Objective-C++ compatibility (#2524 thanks @ianthehenry and @NachoSoto for the review!)
• Fixed race-condition in SignalProducer.sampleOn(SignalProducer) (#2560 #2571 thanks to @neilpa and @NachoSoto!)

Known issues

• Disposing a flattened SignalProducer does not dispose the inner producers (#2453).
• Race condition between concat and take that can lead to one-too-many producers being started (#2548).