core: add EIGENPY_CLASS_HOLDER_TYPE

include/eigenpy/fwd.hpp

@@ -93,6 +93,14 @@
 
 #include "eigenpy/expose.hpp"
 
+#ifdef EIGENPY_WITH_CXX11_SUPPORT
+#include <memory>
+#define EIGENPY_CLASS_HOLDER_TYPE(T) ::std::shared_ptr<T>
+#else
+#include <boost/shared_ptr.hpp>
+#define EIGENPY_CLASS_HOLDER_TYPE(T) ::boost::shared_ptr<T>
+#endif
+
 namespace eigenpy {
 template <typename MatType,
           typename Scalar =