FULLSCREEN Mode

This project now has a 'fullscreen mode' that can be enabled by typing HELP FULLSCREEN at the command prompt (and toggled off using the same command).

Fullscreen mode maximises the viewport space to see the active game window (location, command prompt, and action results messages).  Note that this does not override user-defined behaviours of the browser itself (for example, zoom settings or switching the browser into fullscreen mode) - this only affects the display behaviour of the game, not your browser behaviour.