Added a new Cocoa dynamic framework target target to the main OS X Xcode project. The target is based on the template provided by Xcode. It contains headers and source files in the darwin/ and osx/ subdirectories. Headers are explicitly marked public or project-internal instead of implicitly by subdirectory. Removed the osxsdk target from platform.gypi.
The SDK target has a few dependencies that are managed by mason. Transform the config.gypi generated by configure into an .xcconfig file that Xcode uses to fill in compiler and linker flags.
Added a CI scheme that builds the All aggregate target generated by gyp and the osxapp and SDK test targets.
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