Traffic Generator Updated

With the addition of sixteen local road cars I decided to update the Traffic Generator to have some of the local road cars come back on the layout loaded.  Before this all local road cars stayed off the layout for one session and then came back onto the layout MT via the same interchange they left.  The change I made to the Traffic Generator was to randomly load these cars for local businesses only.  They will still only stay off the layout for one session and they will still always come back on the layout via the same interchange they left.  But now when they return they could be routing to a local business instead of just MT.  This is to represent the capturing of these cars by foreign roads for loads.  It will add more variety to the routings as well as being more prototypical.