Exchange-Keep mixup fixed and layout issues

Cards marked to be kept were being exchanged and vica-versa. Also made the window and keep buttons much wider to prevent the wording on the keep buttons or the dealer's hand (once revealed) from being cut off.

Made some minor clean-up changes in deleting commented out code, removing unused imports and replacing the deprecated "window.show()" with the current "window.setVisible()" in the main method.