How to run model in MPS

If you define the predicate `start()` without parameters in your semantic model, it will be called automatically when you run the model through the context menu in the MPS project.

For example, the following start() predicate in the example about the Autodrome first sets up obstacles and road signs on the autodrome field, and then starts the graphical user interface by calling the another start domain function.

def start() means 
  check all 
    # set walls 
    AutodromeDSL.add wall(5, 1) 
    AutodromeDSL.add wall(5, 14) 
    AutodromeDSL.add wall(10, 8) 
    # set road signs 
    AutodromeDSL.add road sign(4, 5, "south") 
    AutodromeDSL.add road sign(6, 9, "north") 
    AutodromeDSL.add road sign(7, 7, "east") 
    AutodromeDSL.start(10, 500) 
end def