Makes it so that slideshows can have as many files as desired, and
lazily decodes image data in a separate thread to prevent decoding from
stalling the video thread.
Creation of Info.plist files through Xcode is more canonical and
future-proof, as it will automatically pick up changes/updates
introduced by Apple. Non-standard keys can still be added via a
template file, which will then be extended by Xcode with the default
keys.
