Centered Fun

• updated to Swift 5 and latest MacOS
• upgraded WebView to WKWebView
• resizing the nethack terminal to the current games size so it can be centered on the screen - this does (sadly) not mean that the content is perfectly centered. In fact, we center the view the games player has. If the player has a super wide console open, we center that super wide console (which results in nethack visually being displayed more to the right). But hey, better than it always being in the top-left corner only