templatefilters: make json filter handle multibyte characters correctly It aims to fix javascript error of hgweb's graph view in Japanese 'cp932' encoding. 'cp932' contains multibyte characters ending with '\x5c' (backslash), e.g. '\x94\x5c' for Japanese Kanji 'Noh'. Due to json filter escapes '\' to '\\', multibyte string ending with '\x5c' is translated to "xxx\", resulting javascript parse error on a web browser. This patch changes json() to pass unicode to jsonescape(). Unicode decoding error handler changed to 'replace' by Patrick Mézard.