Add support for [[nodiscard]]:

- Decorate container and allocator functions.
- Make sure to disable warnings in tests
- Update doxygen documentation to support it

bench/bench_vectors.cpp

@@ -22,6 +22,11 @@
 #include <boost/move/detail/nsec_clock.hpp>
 #include <typeinfo>
 
+#if defined(BOOST_GCC) && (BOOST_GCC >= 40500)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-result"
+#endif
+
 //capacity
 #define BOOST_INTRUSIVE_HAS_MEMBER_FUNCTION_CALLABLE_WITH_FUNCNAME capacity
 #define BOOST_INTRUSIVE_HAS_MEMBER_FUNCTION_CALLABLE_WITH_NS_BEG namespace boost { namespace container { namespace test {
@@ -30,6 +35,11 @@
 #define BOOST_INTRUSIVE_HAS_MEMBER_FUNCTION_CALLABLE_WITH_MAX 0
 #include <boost/intrusive/detail/has_member_function_callable_with.hpp>
 
+//#pragma GCC diagnostic ignored "-Wunused-result"
+#if defined(BOOST_GCC) && (BOOST_GCC >= 40500)
+#pragma GCC diagnostic pop
+#endif
+
 using boost::move_detail::cpu_timer;
 using boost::move_detail::cpu_times;
 using boost::move_detail::nanosecond_type;