changes in ThreadWeaver signals and slots

[Cyrille Berger]

> This is binary compatible,
Not really, as any binary build with the old kdelibs won't work with the 
newer, and further more I also think it breaks API freeze, as it requires a 
code change in the application.

Now it can be argue wether the change was needed or not, but I still believe 
it should at least have been done on a Monday.

-- 
Cyrille Berger