make sure that we correctly add to the subclasses list for all the modules
make sure that we remove an iclass from its module's subclasses
properly recurse down the class hirearchy
we're not actually using the klass in this function anymore, so nevermind it
avoid calling rb_clear_cache_by_class an extra time here
switch to using linked lists for subclass tracking again
Merge remote-tracking branch 'jamesgolick/klasscache' into klasscache