Preparing for multigrid parameter consolidation and clean up of code, rationalise the different variants.

tests/solver/Test_wilson_mg_mp.cc

@@ -58,7 +58,7 @@ int main(int argc, char **argv) {
 
   RealD mass = -0.25;
 
-  MultiGridParams mgParams;
+  WilsonMGParams mgParams;
   std::string     inputXml{"./mg_params.xml"};
 
   if(GridCmdOptionExists(argv, argv + argc, "--inputxml")) {