* Convert textual frames to/from the currently used character set

The character set is deduced from the locale settings.  It can also be
set explicitly using the --charset option.

* New option --broken-8bit-encoding

Use this option for files where textual frames are stored as
ISO-8859-1, but are actually using another 8-bit encoding.  The
argument to this option is the name of the enchoding actually used.

In query mode, this option helps display such frames properly.

Use it with the --fixup option to fix such frames in the file.

* New option --encoding

Specifies encoding to store textual frames in ID3 tags.

* New option --fixup

Modifies the ID3 v2 tag so that it can be understood by most devices.

* The --convert option can be used to remove unnecessary ID3 formats.

For example, if the file input.mp3 contains both version 1 and 2 tags,
the following will remove version 1 tags:

  idest --convert=2 input.mp3

* Fix processing of unknown frames.

* Fix operation of setpic and pic modules with Guile 2.x.

* Improve documentation