Move [Window] from sdllib.hpp to sdlgui.hpp.
Change name of [Controller] to [ControllerBase].
Convert signed to unsigned to safely handle values such as [point].
Write user-side code to work properly.
Externalize the backup of [_screen].
Move the object of [SDL_Event] from class scope to menber function scope.
Introduce wrapper of [std::array].
Create [Tile], [Kite] and [Dart].
Make more readable [game.hpp] and [game.cpp].
Integrate MVC to [Game].
Update [main].
Modify output format of [PentagonalRational].
Modify constructors of [Kite] and [Dart] to accept [scale].
Add [unique_ptr] and [Tile] related utilities.
Change type of [point] from unsigned to signed.
Correct the mistake of [PentagonalRational::operator*=].
Implement [Model::rotate].