add a node direction to support smooth intersections on nodes with more than just two roads

improve the car positioning by using a prefitted polynom to find the respective t-value

fix bad car behaviour on weirdly shaped roads

make the cars move on roads with a real world space speed

add cars and their routes using the astar search algorithm

add road direction indicator

add spawn- and exit nodes

introduce different node types in preperation for levels

add the ability to remove roads