subparse: Autodetect subtitle text encoding
uchardet to guess the subtitle text encoding if it is not in UTF-8
or manually specified instead of blindly guessing its "ISO-8859-15".
uchardet dependency is optional and when is not available at
compile time, then old behaviour will be used.
uchardet is an encoding detector library, which takes a sequence of bytes in an unknown character encoding without any additional information, and attempts to determine the encoding of the text. Returned encoding names are iconv-compatible.
uchardet library is part of