Add example test program and some changes to make it work

src/isoburn.h

@@ -50,10 +50,9 @@ struct isoburn {
 
  /* Expansion treatment strategy: 1= grow, 2= modify, (any use for 0 ?) */
  int treatment;
-
- /* The options for reading the old image.
-    target_ropts.size will contain the number of blocks of the image. */
- struct ecma119_read_opts *target_ropts;
+ 
+ /* The data source for reading the old image */
+ struct data_source *src;
 
  /* Buffered ISO head from media (should that become part of
     ecma119_read_opts ?) */