Started work on screen fader.
Slight change to userprefs.
Fixed fadeout problem by removing the check for alpha when fading to black. Made the screenStarting boolean public so it can be accessed from outside within the GameManager. Added a InteractionHalted for checking if all user interaction should be halted in GameManager - this can be checked within PlayerController. Right now the only check is for the screen transitions, but I can also see it being used for menus.
Adjusted fade speed.
Merge branch 'feature/level-change-fade' into develop