Update: Highscores, Bubbles and Caustics

Changelog: 

1. New option to enable/disable the water wobble shader, in case someone don't like the effect. 
2. Added water caustic effect.
3. Added bubble particles for the player fish, the moray eel and the bear paws.
4. A highscore is now shown in a tooltip of each level button. Information on whether you have a new highscore is displayed in the level end screen. In addition a total score is shown in the main menu, which is the sum of highscores of all levels.