Update scripts for compatibility with several games running simultaneously

[Diarandor]

Update scripts for compatibility with several games running simultaneously.

This will be needed someday when the engine allows to run several games at once. Although this project may not use that feature, it is better to make scripts compatible, for portability reasons.

Scripts that may need some changes:

• Weather scripts.
• Hud, menus and dialog scripts (maybe). Maybe other scripts too.

[Diarandor]

For the weather scripts, we need to move the initialization of parameters inside the event on_created, and attach all important variables to the game object, somehow.