Basic UI Implemented

https://drive.google.com/file/d/1fALpdSlhOOqAR1QcuBhu2Ytde5kRb_Ud/view?usp=shari...

In this update I have added basic UI such as a menu screen and a death screen. This allows the player to restart the level upon dying. This can be done through pressing the main menu button upon dying, and then pressing "Play Demo". The menu will be graphically updated later on.