[sugar] debugging leaks and performance

[Christopher Blizzard]

Couple of notes.  jdahlin pointed me at this bug:

http://bugzilla.gnome.org/show_bug.cgi?id=348060

which includes some patches for debugging reference counts using 
valgrind.  Something we probably should be using.

Second, Matthias pointed me at his patch that disables using shared 
memory for image transport to the X server.  This is likely to save a 
lot of memory, but we need to see what the performance impact is:

http://mail.gnome.org/archives/performance-list/2006-July/msg00012.html

--Chris