TrafficControl: UI Fixes for Time Visibility

In order to make TrafficControl demo-able, there are some fixes I need to do for the user interface:

• Simplify the time control buttons
• Display the simulated time
• Show the system load (calculation time divided by interval)

Simplifying the time control buttons:

The two spinboxes are not intuitive and should be replaced by only one spin box. The spinbox will contain a double parameter for the forward speed. If that is 1, one second in real time will correspond to one second in simulated time. If that is less than one, the network will move slower. If that is more than one, the network will move faster.

Whenever the value in the new spinbox is changed, a signal is sent to a slot:

The spinbox is defined to accept values from 0,5 to 50, so the check for non-zero denominators shouldn't be necessary. I added the check for futureproofing the code.

I'll discuss the other two changes in the next blog post.