[Amarok] Clean up the EngineController logic.

[Edward Hades]

Alex, looks like you've hit two sparrows with single commit there ;)

For me and Markey, Ogg Vorbis streams do not play (like in progress
bar moves, but there is no sound), but when you hit stop, it fades out
(as pointed out by Markey: "like a zombie sound from hell").

Could you please check and look into it?

-- 
Edward "Hades" Toroshchin,
Aides on irc.freenode.org