* Adds extension to handle interactions with Photos app
- isAuthorized to check/ask for authorization
- saveUIImage to save a UIImage to Photos
* Adds a Pause Menu button for taking game screenshots
* Adds @Feature and @Options for Game Screenshots
* Implements Game Screenshots feature in GameViewController
* Updates project settings
* Passes call to save to Photos as a closure into authorization prompt
- Ensures that the screenshot is saved when the user is first prompted for access to Photos
- More elegant extension code
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Co-authored-by: Riley Testut <riley@rileytestut.com>
Stores SaveState model objects with Core Data, and displays the available save states in SaveStatesViewController.
Currently, tapping + button creates a new save state, while tapping a collection view cell loads the save state, regardless of whether Save State or Load State was selected from the pause menu.
# PauseViewController has been renamed to PauseMenuViewController.
# A new PauseViewController maintains a child UINavigationController, which has PauseMenuViewController as the root view controller.
Additionally, refactored GridCollectionViewCell to no longer use a NIB. This makes it easier to reuse for iOS and tvOS, and allows us to use storyboard segues (which include peek & pop)
