* Refactor: Move classes into their own files
* Handle 404 FileNotFound in UncivServer
* Refactor: Rename method
* Make GameSaver.saveGame throw the exception by default if it is not handled
* Add possibility to work with FileHandles in GameSaver
* Make OnlineMultiplayerGameSaver load the multiplayerServer setting each time it does something
This theoretically makes it unnecessary for the OnlineMultiplayerGameSaver to be re-instantiated each time it is used
* Refactor: Remove duplicated code
* Refactor: Extract NextTurnButton from WorldScreen
* Refactor: Remove WorldScreen-specific code from OptionsPopup
* Use kotlin coroutines everywhere instead of plain threads
This probably also cuts down on our raw thread usage, improving performance, since we now use a cached thread pool (in addition to coroutines being able to reuse threads anyway)
* Improve deep load from notification
* Refactor: Give music download coroutine the proper name
* Gradle build tools upgrade
Apparently the magic is rewriting a specific line in the Android build file and downloading Android SDK 30.0.3
* Added wiki change, isn't that nice :)
Checking the Github actions shows that this doesn't seem to work with the current Github actions due to version confllicts, we'll need to resolve those
