Achievements and guests

Now you can play with your saves created in an unmodded game, but it's better to make a backup copy of the "your_game_folder/game/saves" folder, because the mod can corrupt the files.

Added detailed descriptions of achievements.

Added guest menu where you can see how to get guests.

In the next update, I will focus on choice hints for each chapter in the game and porting the mod to other platforms.