cyclus/cyclus — pull request #1051 by rwcarlsen (2014-12-03 20:12:38+00:00)
Title: fixed prev_decay_time tracking bug. better comments.

* extracted materials now inherit prev_decay_time properly from originating
material. Test for this was added.

* when being absorbed, use prev_decay_time of the material with the larger
quantity.

* added prev_decay_time public accessor to facilitate testing and other
potential uses by archetypes.