Add Simulation class

Main class, connecting other classes and running simulation.
Hold screen surface, all of cars and map.
Clear Car class file.

Remove testing purpose code and parts responsible for image
loading and displaying. PyGame initialization moved into different
file.
Add ImageManager class.

New class is used for loading sprite sheet and draw objects (cut from
sheet).
Add SMap class.

Object of this class can generate, load, save and check maps using in
simulation.
Add drawing methods.

Add draw_car() and draw_map() to image_manager  with cutting
images from spritesheet.
Generate random map and display it.

Changes:

 - fix blitting and objects creating bugs

 - generate random map