A fine-tuning command for indexing the "url.file" and "url.path" sections,
usually for FTP sites, when the sites have national letters in directory
and file names.
Directory and file names (after %XX URL-unescaping) considered to have the
same character set with the one specified in RemoteCharset by default.
This command allows to set an alternative character set for directory
and file names, different from RemoteCharset.