documentation update, added function exception::diagnostic_information, added std::exception to_string overload, removed tabs from source files

[SVN r46697]

example/logging.cpp

@@ -20,6 +20,6 @@ g()
     catch(
     boost::exception & e )
         {
-        std::cerr << e.what();
+        std::cerr << e.diagnostic_information();
         }
     }