Add y, Q2, x, t resolution tests

Relative difference fitted by Gaussian Add sim~rec 2d correlation plot for those variables

benchmarks/dvmp/analysis/vm_invar.cxx

@@ -131,7 +131,7 @@ int vm_invar(const std::string& config_name)
   //================================================================
   //Factorized
   TString VarName[4] = {"y", "Q2", "x", "t"};
-  std::vector<ROOT::TH1D> h_sim;
+  std::vector<::TH1D> h_sim;
   {
   auto h_tmp = d_im.Histo1D({"h_Q2_sim", ";Q^{2};#", 50, hist_range_l[0], hist_range_h[0]}, "Q2_sim");
   h_sim.push_back(h_tmp);