Increased number of AI cars for San Francisco GRiD HQ-Real 1.0 2020-06-01

I made a change to the max number of AI cars for race, increasd frpm 16 to 26. This change doesn't have negative effect on pit stops, but since there are only 15 pit box, some car seems to be graphically superimposed. You can always choose to use a smaller number of cars. Added also an approximate track lenght and width. Put the modified file (ui_track.json) in track folder/UI subfolder, make a backup copy of the original file before.