Check in reader for openqcd configs

This reader is suboptimal in the sense that it opens the entire config on every MPI rank.

tests/IO/Test_openqcd_io.cc

@@ -0,0 +1,55 @@
+/*************************************************************************************
+
+Grid physics library, www.github.com/paboyle/Grid
+
+Source file: ./tests/io/Test_openqcd_io.cc
+
+Copyright (C) 2015 - 2020
+
+Author: Daniel Richtmann <daniel.richtmann@ur.de>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+See the full license in the file "LICENSE" in the top level distribution directory
+*************************************************************************************/
+/*  END LEGAL */
+
+#include <Grid/Grid.h>
+
+using namespace Grid;
+
+int main(int argc, char** argv) {
+  Grid_init(&argc, &argv);
+
+  GridCartesian* grid = SpaceTimeGrid::makeFourDimGrid(GridDefaultLatt(),
+                                                       GridDefaultSimd(Nd, vComplexD::Nsimd()),
+                                                       GridDefaultMpi());
+
+  LatticeGaugeField Umu(grid);
+
+  FieldMetaData header;
+
+  if(!Grid::GridCmdOptionExists(argv, argv + argc, "--config")) {
+    std::cout << GridLogError << "You need to use --config /path/to/openqcd_config" << std::endl;
+    abort();
+  }
+
+  std::string file = Grid::GridCmdOptionPayload(argv, argv + argc, "--config");
+  assert(!file.empty());
+
+  OpenQcdIO::readConfiguration(Umu, header, file);
+
+  Grid_finalize();
+}