2008-04-26 Tatsuhiro Tsujikawa <tujikawa at rednoah dot com>

Added StringFormat class, which internally calls vasprintf.
	operator<< is defined for this class, so it can be used with iostream
	classes nicely. SimpleLogger and following functions are rewritten
	using StringFormat class.
	Besides, now Logger class's methods are non-const, many classes
	that has a const Logger* as a member variable are modified to remove
	const qualifier from the variable declaration.
	* src/HelpItemFactory.cc
	* src/Request.cc
	* src/SimpleLogger.cc
	* src/StringFormat.cc
	* src/StringFormat.h
	* src/Util.cc
	* src/option_processing.cc
	* src/version_usage.cc
	* test/StringFormatTest.cc
	* src/*.h: The classes that has const Logger* as a member variable.

src/DefaultExtensionMessageFactory.h

@@ -49,7 +49,7 @@ private:
 
   SharedHandle<Peer> _peer;
 
-  const Logger* _logger;
+  Logger* _logger;
 
 public:
   DefaultExtensionMessageFactory();