libcanberra: update, streamline dependencies

Still some ToDos but should be OK, tested building some
reverse-dependencies.
libcroco: move to gnome-3, minor update
libgsf: update, streamline dependencies, drop obsolete patch

Tried to build some affected packages, seems OK.
librsvg: drop gtk2 dep. by default, add optional gtk3 dep.

Tried to build some affected packages, seems OK.
goffice: update, move to gnome-3 (needs gtk-3 now)

+fix gnucash to work with new intltool
gnumeric: update
gnome2.libart_lgpl: update
fixup! goffice: update, move to gnome-3 (needs gtk-3 now)