Bullet Time - In-game Score, Time and High Scores

Added the score and time display for use in level scenes.  This uses the Unity UI as shown below:

Also added and end of level display with high score table functionality:

These elements are important for providing feedback to players as well as completing the overall game experience - from menu, to game level and back again.

The game timer is set to end the level if time expires and the initial time can be set from the inspector in Unity, meaning it should be easily re-useable in further scenes.