Update to TickData and condition handling in the simulation loop and tick.

• Added TickReturn as datalcass to collect returnvalues from tick. This is used to update the TickData which is yielded from run_simulation.
• updated tracking of need for reschedule
• updated run_simulation loop such that each functions returns its values that are needed to build the TickData. These are then finally used to construct the TickData class. The state is therefore more transparent. And updates are certain to be the latests when yielding. The 5. step "complete the timestep" is last, after yield (as it is equivalent to the update condition in a for loop (i=0;i<X;i++))

Missing to complete Issue#74: checking for initializaion of the time-delta

The initialization of time-delta as mentioned in Issue#74 is not going to be tackled, as further discussion on frequency of running sub simulations vs general time-delta needs to be resolved.