guile-debugging demo and 0.9 release

[Neil Jerram]

I've prepared a brief demo showing how my guile-debugging package can be 
used to single-step through some of GnuCash's scheme code.  This is now 
up at http://www.ossau.uklinux.net/guile-debugging/demo/shot0.html.

I've also released version 0.9 of guile-debugging, with some 
improvements that I made while preparing this demo.  The new .tar.gz is 
available at http://www.ossau.uklinux.net/guile-debugging-0.9.tar.gz, 
and its NEWS excerpt follows.

Regards,
        Neil


* Tweaks to make single stepping more intuitive

When Guile is told - by either "step-file" or "step-over" - to run
until the exit of a particular evaluation/application, guile-debugging
now presents the stack trace at the exit point so that the frame for
that evaluation/application is automatically selected.  This means
that a subsequent "step-file" command refers to the source file of
that evaluation/application, which is usually what the user wants.

(Previously guile-debugging selected the innermost frame.  Because of
tail recursion, which means that an exit operation can pop several
stack frames at once, this innermost frame is often different from the
frame that the user asked to run to the exit of.)