Set correct index for final nuclides in restart tests
Set correct index for final nuclides in restart tests

Many repetitions of the following change:

-    assert y1[3] == approx(s2[0])
-    assert y2[3] == approx(s2[1])
+    assert y1[2] == approx(s2[0])
+    assert y2[2] == approx(s2[1])

This causes many of the restart tests to fail, because all
schemes but the predictor save repeated data under restart conditions.
Performing one normal depletion event, non-restarted, and then
one restart event, as these tests do, should produce vectors for
time and densities like:
   t = [t0, t1, t2]
   a = [a0, a1, a2]
            |    ^ after restart
            ^ non-restart run
With this, the current tests would fail due to an IndexError, as
the atom vectors should only have three elements. Instead,
non-predictor schemes return vectors
   t = [t0, t1, t1, t2]
   a = [a0, a1, a1, a2]
and one can access a[3] to obtain the desired EOS concentrations.

liangjg/openmc,walshjon/openmc,walshjon/openmc,paulromano/openmc,shikhar413/openmc,smharper/openmc,smharper/openmc,mit-crpg/openmc,smharper/openmc,walshjon/openmc,liangjg/openmc,smharper/openmc,shikhar413/openmc,liangjg/openmc,liangjg/openmc,paulromano/openmc,amandalund/openmc,amandalund/openmc,walshjon/openmc,mit-crpg/openmc,shikhar413/openmc,paulromano/openmc,amandalund/openmc,mit-crpg/openmc,mit-crpg/openmc,paulromano/openmc,amandalund/openmc,shikhar413/openmc