(models) slight change in graph ordering API (abstract vertices list)
ReversePostOrder returns an iterator of a reverse view of the list
(oops) dependency solver used DFS pre-order, not reverse post-order :-/
forgot to update copyrights
removed unnecessary finder class, improved reverse post-order for roots
dependency solver sorts functions too, now.
reverts commit 66dd02abc107b88ed2387ca4089ba168cac40aca
Apparently there was a problem at some point, I could not reproduce it,
maybe it was simply caused by the wrong ordering?
updated to version 0.15.0