EffectsHandlerImpl connects to the Workspace signal clientActivated.
The emitting of the signal is slightly moved from before the activation logic
to after the activation logic. This might change behavior in the scripting
component, but the previous code looked wrong.
Client and Unmanaged use a signal to notify that they are about to be closed.
The EffectsHandlerImpl is connected to those signals and emits the appropriate
windowClosed signal to which the effects are connected.
All previously existing windowAdded methods are renamed to slotWindowAdded.
EffectsHandlerImpl is connected to Workspace's clientAdded signal, which is
emitted a little bit earlier than the previous direct method call. This might
change behavior.
Another signal is added to Workspace to signal that an unmanaged is added.
