Moved from reference counting over to a mark and sweep method. Objects
are now required to implement an allRefs method which returns a pointer
to a list of all other referenced objects. How the list is maintained
is up to each object. The retain/release mechanism still works; objects
with any references will not be garbage collected, even if the collector
thinks they should be.
an incremental, reference counting garbage collector for QFobjects. A
different kind of collector will eventually be needed to run once in a
while to sweep up cyclic structures.
