Replace 'void' template arguments in Mesh class with EmptyData and remove
the specialization of MeshElement with 'void' data.
Using EmptyData in TriangleMeshTest and TetraheronMeshTest.
Revision based on Coding Standards
Merge branch 'feature/EmptyData-refactor' of git.assembla.com:OpenSurgSim into feature/EmptyData-refactor
Fix CppLint warning