get_error_info returns raw pointer instead of shared_ptr (breaking change)

diagnostic_information can now be called with boost::exception or std::exception object.
BOOST_THROW_EXCEPTION can now be used even if exceptions are disabled.
added functions: current_exception_diagnostic_information, current_exception_cast
documentation updated to match.

[SVN r52225]

test/current_exception_cast_test.cpp

@@ -0,0 +1,47 @@
+//Copyright (c) 2006-2008 Emil Dotchevski and Reverge Studios, Inc.
+
+//Distributed under the Boost Software License, Version 1.0. (See accompanying
+//file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/exception/current_exception_cast.hpp>
+#include <boost/detail/lightweight_test.hpp>
+#include <exception>
+
+class
+my_exception:
+    public std::exception
+    {
+    };
+
+class
+polymorphic
+    {
+    virtual
+    ~polymorphic()
+        {
+        }
+    };
+
+int
+main()
+    {
+    try
+        {
+        throw my_exception();
+        }
+    catch(
+    std::exception & e )
+        {
+        try
+            {
+            throw;
+            }
+        catch(
+        ...)
+            {
+            BOOST_TEST(boost::current_exception_cast<std::exception>()==&e);
+            BOOST_TEST(!boost::current_exception_cast<polymorphic>());
+            }
+        }
+    return boost::report_errors();
+    }