Added Flush() to concept stream. Add this new member function to all streams.

Writer and PrettyWriter automatically calls Flush() at the end of JSON text.

git-svn-id: https://rapidjson.googlecode.com/svn/trunk@27 c5894555-1306-4e8d-425f-1f6f381ee07c

example/pretty/pretty.cpp

@@ -24,6 +24,5 @@ int main(int argc, char* argv[]) {
 		return 1;
 	}
 
-	os.Flush();
 	return 0;
 }