Soundfont updates

[Stefan Westerfeld <stefan space twc de>]

   Hi!

After our last discussion, I've updated the wip/soundfont branch in stwbeast
repo again. Summary

  * GList changed to std::vector
  * all data members moved to C++ SoundFont*Impl classes
  * make check fixed (use search path to resolve relative paths)

I initially had problems with the order of the destruction, see comment in
commit 9f477e70e1d7b7b90d8b3bb31d5bded75ddf8b09, as the container
release_children runs after the C++ implementation object was destroyed, and
therefore can't access the state.

What I did to resolve the problem was to move bits and pieces from
*_release_children, *_dispose and *_finalize to the C++ implementation
destructor, so these functions don't need to access the state.

Anything else missing for merging SF2 support?

   Cu... Stefan
-- 
Stefan Westerfeld, http://space.twc.de/~stefan