Full Screen, Menu Navigation & Volume Update

FULL SCREEN
Game can now be played full screen. This was not previously possible because of now fixed UI issues. 

MENU NAVIGATION
The menu is now navigated via the keyboard, accompanied with help text on the top left of the main menu. This patch now makes The Resistance a keyboard only game.

VOLUME BALANCING
Reduced the volume of the menu select, shoot, and heal sound effects which was overpowering the music.

If you come across any issues, a comment here, or in the comment section below the game would be highly appreciated.