Fixed 4d fermion gparity force. Put strong tests on make check force tests

tests/forces/Test_dwf_gpforce.cc

@@ -212,6 +212,7 @@ int main (int argc, char ** argv)
 
   std::cout << GridLogMessage << "Total dS    "<< Hmomprime - Hmom + Sprime - S <<std::endl;
 
+  assert( fabs(real(Sprime-S-dSpred)) < 1.0e-2 ) ;
 
   std::cout<< GridLogMessage << "Done" <<std::endl;
   Grid_finalize();