[Libcdio-devel] UDF file reading is working a bit more

[R. Bernstein]

With the last round of commits, I am able to extract a file from a UDF
image. I think previously I had directory listing largely working (and
I don't think I've broken it since then.)

For now the sample program udf2 lists the contents of a file. 

What's needed in the library is to remember a position in a file so
that subsequent reads continue from where we last left off. The idea
was to try to make things look like the standard read routine.

The UDF spec is huge, and it is quite possible if not likely that
there are huge gaps. On the other hand it's also possible that most
UDF images use only a small fraction of what's there, so the small
fraction that's implemented is good enough.