Documentation fixes:

- core.hpp: hide non-public macros
- default_delete.hpp: Hide detail code
- unique_ptr.hpp: Likewise
- utility_core.hpp: Document move_if_not_lvalue_reference

include/boost/move/default_delete.hpp

@@ -31,6 +31,7 @@
 //! Describes the default deleter (destruction policy) of <tt>unique_ptr</tt>: <tt>default_delete</tt>.
 
 namespace boost{
+// @cond
 namespace move_upd {
 
 namespace bmupmu = ::boost::move_upmu;
@@ -96,6 +97,7 @@ typedef int bool_conversion::* explicit_bool_arg;
 #endif
 
 }  //namespace move_upd {
+// @endcond
 
 namespace movelib {
 
@@ -123,7 +125,11 @@ struct default_delete
    #endif
 
    #if defined(BOOST_MOVE_DOXYGEN_INVOKED)
+   //! Trivial copy constructor
+   //!
    default_delete(const default_delete&) BOOST_NOEXCEPT = default;
+   //! Trivial assignment
+   //!
    default_delete &operator=(const default_delete&) BOOST_NOEXCEPT = default;
    #else
    typedef typename bmupmu::remove_extent<T>::type element_type;