
Example: adding jpeg

0.  cd vil1/file_formats
1.  cp vil1_pnm.h vil1_jpeg.h
2.  replace pnm with jpeg
3.  implement
       read_header
       do_get_section()
       write_header
       do_put_section()

n-1. add file_formats/vil1_jpeg.cxx to vil1/makefile
n.  add vil1_jpeg to vil1/vil1_file_format.cxx
