change extern to namespace to get around clang bug.
changed namespacing to fix clang bug
Merge pull request #190 from Astron/bugfix/clang-fix-constraints

changed namespacing to fix clang bug
Merge pull request #191 from Astron/feature/clang-fix-dcclass

change extern to namespace to get around clang bug.
Merge branch 'master' into bugfix/unittest-cleanup