Change package name to traffic_simulator
Use same-size buffer canvas instead of a scaled world canvas

It is expected to be smoother for large scale maps
since no large canvas is drawn.

However now it is more flickering than before when
drawImageScaledFromSource() was used. Too bad.
Enhances the camera function

It can be setCenter(), reset(), and toCenter().
Modifies the initial view of the map
Change the API of creating a road
Change camera setCenter API

Great, the new rendering way can indeed show a bigger map without lagging.