[cleanup] Remove nullptr fallback and deprecate header.

Nothing needs to be included with proper C++11 compilers.

dune/common/nullptr.hh

@@ -3,55 +3,12 @@
 #ifndef DUNE_NULLPTR_HH
 #define DUNE_NULLPTR_HH
 
-/** \file
- * \brief Fallback implementation of the nullptr object in C++0x
- */
-
-#if ! HAVE_NULLPTR
-
-/**
-   \brief Fallback implementation of nullptr
-
-   see C++ proposal
-   http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2431.pdf
- */
-const                        // this is a const object...
-class dune_nullptr_t {            // of type nullptr_t
-public:
-  template<class T>          // convertible to any type
-  operator T*() const        // of null non-member
-  { return 0; }              // pointer...
-  template<class C, class T> // or any type of null
-  operator T C::*() const    // member pointer...
-  { return 0; }
-private:
-  void operator&() const;    // whose address can't be taken
-} nullptr = {};              // and whose name is nullptr
-
-namespace Dune {
-  typedef dune_nullptr_t nullptr_t;
-}
-
-template<class T>
-bool operator == (T* t, dune_nullptr_t)
-{
-  return (t == static_cast<T*>(nullptr));
-}
-
-template<class T>
-bool operator == (dune_nullptr_t, T* t)
-{
-  return (t == static_cast<T*>(nullptr));
-}
-
-#else
-
 #include <cstddef>
 
 namespace Dune {
   using std::nullptr_t;
 }
 
-#endif // HAVE_NULLPTR
+#warning The header dune/common/nullptr.hh is deprecated. Just remove the include.
 
 #endif // DUNE_NULLPTR_HH

dune/common/shared_ptr.hh

@@ -6,7 +6,6 @@
 
 #include <memory>
 
-#include <dune/common/nullptr.hh>
 #include <dune/common/typetraits.hh>
 /**
  * @file

dune/common/stdthread.hh

@@ -4,7 +4,6 @@
 #ifndef DUNE_COMMON_STDTHREAD_HH
 #define DUNE_COMMON_STDTHREAD_HH
 
-#include <dune/common/nullptr.hh>
 #include <dune/common/unused.hh>
 
 namespace Dune