MNT: Added __init__.py file to the nsls2.io package and fixed setup.py to
include the nsls2.io package
init of data structure for xrf fit
add calculations of cs, line_energy, jumpfactor
add element data file to save data as dict
add license
add more docstring
MNT : PEP8 white-space fixes
MNT : re-factored back end data structures

 - turned OTHER_VAL into a dict keyed on both
   the symbol and Z
 - simplified the data look up in Element
MNT : simplified handling of energy

  - just try to cast to float.  Let python deal with the conversion.
    If it can't be done it will raise an exception.
MNT : use np.nan for missing values

I am interpreting 0 in the density of Fm as meaning 'not enough of this
has ever been made'.  Use np.nan so that computations using this value
will fail (yield nan), rather that silently, but incorrectly, work.
ENH : make any cases work for element symbols

force all string inputs to be lowercase when keying the
dictionary.
correct name and add more docstring
add unit
add attributes and parameters
add __repr__ and add examples
add smoke test for all elements, add ----
BLD : Make sure new modules are in setup.py
TST : use conda to build xraylib for testing

 - this required shortening the install path due to swig
MNT : re-added missing module in setup.py
MNT : version bump for tagging