Solarutils

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* add documentation
* add BSD 3-clause license
* add NREL license and disclaimers
* fix 5 - Wheel made after ``build_ext`` doesn't contain libs

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* one source for all platforms

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* fixes ``rpath`` issue with darwin

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* compatibility with Python-3

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* fix package names not platform specific
* change linux to linux2 everywhere

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* Linux x86-64 wheel with binaries in addition to MS Windows x86-64 wheel
* fixed some namespace clashes
* changed ``solar_utils.py`` to ``core.py``
* changed ``solar_utils_exceptions.py`` to ``exceptions.py``
* conformed to variable naming conventions, removed camelcase, use underscores
* change use of builtin keyword ``code`` as variable to ``err_code``