version 0.4

* added "loop" track
* fixed "car" track
* fixed "hairpins" track
* added boss key (thank you Christophe Sauthier)
* tracks server (client can now download new tracks when they are available)
* improved network protocol
* added a framework to program bots
* first bot for the game : "Anticip"
* fixed memory management (server and client release memory when changing track)
* generic Makefile (easier to compile Linux/Windows binaries)
* network startup was fixed to avoid to much delay between clients and server
* fixed a bug when sending keys for record validation
* also send records in network mode
* game and network protocol are now endian safe (thank you Markus W. Weissmann)