This MR replaces CMAKE_PROJECT_NAME with PROJECT_NAME within SMTK so SMTK
will build and install as a third party submodule of CMB. Also, the
"subproject" delineation was removed from cJSON (which will soon be removed
entirely), SMTKVTKExtensionMeshing, and SMTKDiscreteModel. Finally, the
header test macro has been modified to accept as input the library
associated with the header files.