New extension to support problematic MBCS on Windows. The aim of this extension is to clear the problem related to having 0x5c in 2nd byte of encoded bytes. So this extension is usefull for: * Japanese Windows user shift_jis encoding. * Chinese Windows user using big5 encoding. To use this extension, simply enable it without any customization. Note that some important python built-in functions and mercurial functions are altered for this extension to convert argument if need to handle MBCS.