* [core] Add interface to get image from sprite atlas
* [tests] Add tests for Map::getImage
* [ios, macos] WIP: get MGLImage for name from style
* [ios, macos] Fixed -imageForName:
Convert from sprite images to platform images using the existing encodePNG() function, which is also used for printing. Allow -imageForName: to return nil without an assertion failure. Added a basic test.
ios.xcodeproj is an ordinary Xcode project with ordinary Xcode targets for iosapp and ios-bench, all contained in an ordinary Xcode workspace that happens to also reference the gyp-generated platform.xcodeproj. The iosapp target links to and embeds Mapbox.framework, which is a product of the gyp-generated platform.xcodeproj. ios-tests.xcodeproj is also in the workspace, enabling simultaneous debugging of KIF tests, the SDK, and core code.
Moved storyboards into Base.lproj and image assets into an asset catalog. Removed iOS 6 assets from the iosapp asset catalog. Moved the original ios-bench application icon SVG into a non-project location.
Removed app/Settings.bundle, which is identical to framework/Settings.bundle.
Removed a broken reference to an unused header from the ios-tests project.
