transition event sound properties

[HUECYCLES]

adds:

• reverse_splat.wav
• self.lancer and self.lancer_exit bool properties
• self.door bool property
• self.sound and self.pitch string properties

[NyakoFox]

I think just adding a generic sound to play property is better than adding more boolean properties.

[HUECYCLES]

ah ok, what about the door sound tho? since it's two sounds in one

[NyakoFox]

I implemented it in my fangame using two properties, one for when you touch the transition and one for when you're about to go to the next map.