Completely removed NiallsCPP11Utilities.hpp

No code in Int128_256 relies on anything from NiallsCPP11Utilities anymore. The submodules, and NiallsCPP11Utilites.hpp can now be removed(as long as this passes on travis). Some clean up is required in the remaining files, fixing macros, making naming conventions congruent to boost policy, etc.

TODO:
1. Remove extra files and sub-modules
2. Rename/relocate files as needed
3. Determine if Int128_256 can be replaced by its SHA256 c implementation and update as necessary
4. Update the travis.yml to account for all the changes, and implement Nialls suggestions