TrafficControl: Adding Menu, Toolbar and Statusbar

After adding button icons to the user interface, I've moved them to a menu and a toolbar.

Adding buttons to a toolbar is quite straight forward. I added the spinbox to the toolbar in the source code.

I have disabled the button "step one second" when the simulation is running.

The text related to the action/button changes when the state changes between running and paused,

The messages (time and time consumption) were added to the statusbar from the source code too.

The next step will be to ad a second toolbar that will control the different widgets.