version 0.5

* added "formula" track (thank you Julien)
* added some new car sprites (thank you Julien)
* added collisions between cars in network mode
* added a synchronization check between server and clients
* added informations about missed checkpoints and wrong laps (thank you Julien)
* added car lights (red lights, backwards lights, warnings)
* added night mode with car night lights
* fixed a bug with Win32 version downloading new tracks
* fixed SDL_Init(0) in bot framework
* use SDL_GetRGB and SDL_MapRGB to handle colors