better error handling, adding ENDFDataSource.reaction that uses rxname to accept all rx
discretized tweaks, api improvement
Merge remote-tracking branch 'upstream/staging' into staging
Add basic hashing of nuc_data.h5

This commit includes functions to generate the hashes for each dataset,
functions to generate hashes using nuc_data_make, and a current hash of
nuc_data.h5 datasets.
Improve PEP 8 compliance
Make hashing functions more concise and move hashes to c++

As was discussed the hashing functions have been made more concise and
combined into a single file. The stored hashes have been moved to
data.cpp and are accessible through pyne.data. Docstrings were also
added.
PEP8 style changes to nuc_data_make

remove lots of trailing spaces at the end of lines and adding spaces
after commas and between +’s.
Use data_checksums instead of hash in c++; remove _ from hashtools.py

In addition made initialization internal to c++
Add basic test of data_checksums
This makes pictures but has Physics Problems
moving discretize back into ENDFDataSource
Merge remote-tracking branch 'upstream/staging' into staging
ENDF discretization should work, actually, for real, this time.
changing Eint to e_int because lowercase, adding slight docs
slight commenting
PEP8
docfix
Added missing 'np.' to 'e'
Update ENSDF data and add small fix on ensdf.half_life.
made some import paths relative.