differences with FDC for forward and backward runs persist

[jfburkhart]

Working with a Forward run::

In [106]: fd.max()
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-106-dcfda479542d> in <module>()
----> 1 fd.max()

~/.conda/envs/shyft/lib/python3.6/site-packages/reflexible-0.5.0-py3.6.egg/reflexible/data_structures.py in max(self)
    667     @property
    668     def max(self):
--> 669         return self.time_integrated.max()
    670 
    671     @property

AttributeError: 'FDC' object has no attribute 'time_integrated'

In [107]: fd.min
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-107-18303f3bb83f> in <module>()
----> 1 fd.min

~/.conda/envs/shyft/lib/python3.6/site-packages/reflexible-0.5.0-py3.6.egg/reflexible/data_structures.py in min(self)
    671     @property
    672     def min(self):
--> 673         return self.time_integrated.min()
    674 
    675