Added missing headers to Copy Files step of Kiwi target build.

A number of headers have been added to the project recently, but many of them didn't get added to the Copy Files step in the "Kiwi" target, so they were not included in the output for the iOS framework build. (Haven't tried building for OS X, but the same script may be used there as well.) This caused an error when including "Kiwi.h" in a project, because it would try to import the missing files.

The simple change here to the project file adds the missing files back and fixes the framework build for me.