Change SimTK_NICETYPENAME_LITERAL macro to open and close the SimTK:: namespace so that C++11 won't complain about a template specialization occuring outside the namespace where the original template was defined.

Note: this will no longer work properly if expanded inside the SimTK namespace!
Merge pull request #143 from simbody/fix_SimTK_NICETYPENAME_LITERAL

Change SimTK_NICETYPENAME_LITERAL macro to use SimTK namespace