Keyboard Controls for Menu

Realized that in a game focused on typing, having to use the mouse to navigate menus wasn’t the most intuitive option. Added the ability to traverse all menus using the arrow keys - pressing enter will select the currently chosen level. Mouse controls also work, and will override keyboard controls if the user hovers over a menu option and tries to use the keyboard to select other options. The first entry in the menu is selected by default, meaning that players will easily be able to retry their runs by simply pressing the enter key.