WillOWisp: Scripting is broken

[maxteufel]

WillOWisp objects don't seem to get properly added to the scripting interfaces.

AN ERROR HAS OCCURED [the index 'willo2' does not exist]
[SQUIRREL] 
CALLSTACK
[SQUIRREL] *FUNCTION [main()] Sector main - ScriptTrigger line [2]
[SQUIRREL] 
LOCALS
[SQUIRREL] [vargv] ARRAY
[SQUIRREL] [this] TABLE
[WARNING] /home/mteufel/src/games/Tux/supertux/src/scripting/time_scheduler.cpp:60 Error waking VM: the index 'willo2' does not exist

Test: Ghost Forest Transition in Test Collection.