feature: add fullscreen capability

[SenaJesus]

many gamers want to play game without distractions, so I will add a feature that will enable play the game in fullscreen using the key f11. it will also work to exit to fullscreen by pressing the same key (f11).

[monacofj]

Was this issue already already selected by the time we've frozen v1.1.0?
Or is it a new wished feature?