Stop sounds when switching to the next scene

[Cyber Killer]

Some sounds are played too long when the player skips to the next scene. Make them fade out when the next scene is shown.

some examples:
- dripping water should stop when the intersection is reached
- running rats should stop when another instance of the intersection menu is shown or if the player falls
- monster eating in the bad ending should stop when the credits are displayed

Probably more, please check all sounds.

Found in 0.2