Nonvirtual member functions

• int read_coor_file(char *, int, int=(-1), int=(-1), int=(-1)) - request to read in the specified file. The second argument is the type, and the remaining are the beginning frame, ending frame, and frame skip values. If any are not specified or are < 0, default values are used.
• write_coor_file(char *, int, int=(-1), int=(-1), int=(-1)) - same as above, but requests to write out a file.