[move] move shared_from_this.hh to the correct folder

after cherry picking shared_from_this.hh from dune-functions, we move
it to correct folder and adapt the file

dune/common/CMakeLists.txt

@@ -82,6 +82,7 @@ install(FILES
 	promotiontraits.hh
         reservedvector.hh
         shared_ptr.hh
+        shared_from_this.hh
         singleton.hh
         sllist.hh
         static_assert.hh

dune/common/Makefile.am

@@ -79,6 +79,7 @@ commoninclude_HEADERS = 			\
 	propertymap.hh				\
 	reservedvector.hh			\
 	shared_ptr.hh				\
+	shared_from_this.hh			\
 	singleton.hh				\
 	sllist.hh				\
 	static_assert.hh			\

dune/functions/common/shared_from_this.hh → dune/common/shared_from_this.hh

 // -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 // vi: set et ts=4 sw=2 sts=2:
-#ifndef DUNE_FUNCTIONS_COMMON_SHARED_FROM_THIS_HH
-#define DUNE_FUNCTIONS_COMMON_SHARED_FROM_THIS_HH
+#ifndef DUNE_COMMON_SHARED_FROM_THIS_HH
+#define DUNE_COMMON_SHARED_FROM_THIS_HH
 
 #include <memory>
 #include <dune/common/shared_ptr.hh>
 
 namespace Dune {
 
+  /** @addtogroup Common
+   *
+   * @{
+   */
+
   /* \brief Mixin class similar to std::enable_shared_from_this, but compatible with stack-allocated objects.
    *
    * This mixin class extends std::enable_shared_from_this to make it compatible with objects
@@ -78,6 +83,7 @@ namespace Dune {
     mutable shared_ptr<T> _local_ptr;
   };
 
+  /** @} */
 } // end of namespace Dune
 
-#endif // DUNE_FUNCTIONS_COMMON_SHARED_FROM_THIS_HH
+#endif // DUNE_COMMON_SHARED_FROM_THIS_HH