molton's VSXu changes / additions

Added 2 functions, one called add_visual_path that adds more visuals to the list of visuals from a user specified directory, specified as an argument to the function, and one called pick visual that takes an integer argument that is a specific visual based on the index of available visuals. (pick_visual(int) in vsx_manager.cpp, select_visual(int) in vsx_statelist.cpp)