Charge conjugation boundary conditions for gauge fields implemented as a policy

class, changing the nature of covariant Cshifts used in
plaquettes, rectangles and staples.

As a result same code is used for the plaq and rect action independent of the BC type.

Should probably isolate the BC in a separate class that Gimpl takes as a template param.
Do the same with smearing policies.

This would then allow composition of BC with smearing etc....

tests/Test_hmc_GparityIwasakiGauge.cc

@@ -0,0 +1,53 @@
+#include "Grid.h"
+
+using namespace std;
+using namespace Grid;
+using namespace Grid::QCD;
+
+namespace Grid { 
+  namespace QCD { 
+
+
+class HmcRunner : public ConjugateNerscHmcRunner {
+public:
+
+  void BuildTheAction (int argc, char **argv)
+
+  {
+    UGrid   = SpaceTimeGrid::makeFourDimGrid(GridDefaultLatt(), GridDefaultSimd(Nd,vComplex::Nsimd()),GridDefaultMpi());
+    UrbGrid = SpaceTimeGrid::makeFourDimRedBlackGrid(UGrid);
+  
+    FGrid   = UGrid;
+    FrbGrid = UrbGrid;
+
+    // temporarily need a gauge field
+    LatticeGaugeField  U(UGrid);
+
+    // Gauge action
+    ConjugateIwasakiGaugeActionR Gaction(2.6);
+
+    //Collect actions
+    ActionLevel<LatticeGaugeField> Level1(1);
+    Level1.push_back(&Gaction);
+    TheAction.push_back(Level1);
+
+    Run(argc,argv);
+  };
+
+};
+
+}}
+
+int main (int argc, char ** argv)
+{
+  Grid_init(&argc,&argv);
+
+  int threads = GridThread::GetThreads();
+  std::cout<<GridLogMessage << "Grid is setup to use "<<threads<<" threads"<<std::endl;
+
+  HmcRunner TheHMC;
+  
+  TheHMC.BuildTheAction(argc,argv);
+
+}
+