Use standard plusgin directory and create plugin library

DDCore/src/StandardPlugins.cpp

-// $Id:$
-//====================================================================
-//  AIDA Detector description implementation for LCD
-//--------------------------------------------------------------------
-//
-//  Standard plugins necessary for nearly everything.
-// 
-//  Author     : M.Frank
-//
-//====================================================================
-
-// Framework include files
-#include "DD4hep/Factories.h"
-#include "DD4hep/LCDD.h"
-// ROOT includes
-#include "TGeoManager.h"
-#include "TGeoVolume.h"
-
-using namespace std;
-using namespace DD4hep::Geometry;
-
-static long display(LCDD& /* lcdd */,int argc,char** argv)    {
-  TGeoManager* mgr = gGeoManager;
-  const char* opt = "ogl";
-  if ( argc > 0 )   {
-    opt = argv[0];
-  }
-  if ( mgr ) {
-    mgr->SetVisLevel(4);
-    mgr->SetVisOption(1);
-    TGeoVolume* vol = mgr->GetTopVolume();
-    if ( vol ) {
-      vol->Draw(opt);
-      return 1;
-    }
-  }
-  return 0;
-}
-DECLARE_APPLY(DD4hepGeometryDisplay,display);
-
-static long load_compact(LCDD& lcdd,int argc,char** argv)    {
-  for(size_t j=0; j<argc; ++j) {
-    string input = argv[j];
-    cout << "Processing compact input file : " << input << endl;
-    lcdd.fromCompact(input);
-  }
-  return 1;
-}
-DECLARE_APPLY(DD4hepCompactLoader,load_compact);
-