Add global listeners for a simulation

[jiracekz]

Now, when one task listener is needed for the whole simulation, it should be added to a single Runtime. It could be useful to have a method that would assign to a listener to the simulation, just for semantical clearence.

[iliasger]

We need to add hooks to important places in the runtime, e.g. the scheduler.
Zbynek will provide an example of what information should be needed for the hook.