data_source now can grab E_g from ENDF File 3
implemented _load_reaction & tests
implemented _load_reaction & tests
cleaned up list comprehension of numpts
changed ENDF reader example for fun and profit
First pass at integrating energy ranges
Indexing-based integration. Lin-log, log-lin, and log-log to come soon.
Test cases for linear and histogram
Moved integrators into top-level; linlin and histogram normalize now
Added docs for interpolation math, implemented lin-log
Trying to fix discontinuities.

Using masked arrays to ignore NaNs from 0-width sections,
which are generated by discontinuities. When summed, masked
constants are treated as 0 in iPython notebook. However
sum() spits out "masked" when actually tested...
Attempt at fixing interpreter finding.
Fixed summing, added more integrations

Fixed summing masked arrays and added integration code and math
documentation for loglin interpolation. No tests for loglin or
loglog yet.
Fixed typo in dbgen.atomic_weight.
First stab at Special ENDF Interpolation
Wrote tests for interpolation schemes 1-5
Implemented discretize in data_source.py for ENDF.
Changed xs_gs to dst_sigma to fit in better.
Some minor updates
updeated endf example