Merge lexical_cast from trunk:

* fixed #6717 (now lexical_cast won`t try to support non confirming swprintf)
* fixed #6670 (now using BOOST_NO_UNICODE_LITERALS macro to detect unicode literals support)
* rewritten Jamfile

[SVN r77804]

test/lexical_cast_no_exceptions_test.cpp

@@ -29,7 +29,7 @@ bool g_was_exception = false;
 namespace boost {
 
 void throw_exception(std::exception const & ) {
-	g_was_exception = true;
+    g_was_exception = true;
 }
 
 }