1.01.29: Directional lighting for meshes

Now there is optional mesh directional lighting. You can enable this with Options -> Engine -> Rendering. You can change the min and max lighting values. Also note that in the same place you can easily turn on anisotropic filtering (before you needed to do this from the console or program_startup.txt).

Various improvements have been made to the chunk file database for saved games. For example, we now wait to process "remove chunk file requests" until the player saves the game.