A build tree kept beside the data can be chosen in the settings, and when no
simulator is found the starter asks for one instead of calling the
installation broken. The simulator now runs in the installation, not in the
folder of its binary, and a binary for the other system is no longer refused.
VehicleDatabase becomes VehicleCatalog, Physics becomes VehiclePhysics, and the
textures.txt and .fiz parsers move to Infrastructure. GameLibrary replaces the
GameData singleton.