made engine part
some code clean up

commented out timer printf
indented stuff
made an isAirborn() function. kart is airborn unless it collided with scenery object that update step. made kart not accelerate when airborn (which means it wont get airborn unless you turn on wings AFTER you are going fast enough)
Merge branch 'master' of https://github.com/Milez213/CityTrial