Remove level hack in half_life()

Also skip over unused datasets and use direct float conversion of
energy level.
constrain level continuation parsing so unknown br's aren't returned
get rid of unused _level_regex and refactor _level_regex2 to _level_regex
remove duplicate levels in half_life() test
return keV instead of MeV from level_record
number levels by energy not by metastable state number

Also update tests accordingly
fixes to origen_data for updated level record parsing

adds state and fixes the test to check for levels in keV not MeV
Add final ensdf record parsers
I searched and replaced all molecular_weight and replaced them with molecular_mass
updating comments
updating comments and adding back liscense.txt
added base tape9 and cache.load() optimization which makes the cli run in a minute, rather than an hour.
alost there
first-cut origen transmuter
Origen runs, but segfaults
added more sensible default values
origen fails with read error
Initial add of ssw_combine.py example
origen transmuter works...but not with base_tape9.inp
lost roundtripability of writing in favor of robustness