uses modified version of id3lib-3.8.3
modifications made:
	- added some explicit typecasts
	- fixed vbr header read
	- added support for additional TXXX frames
	- added ability to search in TXXX frames for key names
	
unicode, utf-8, ISO-8859-1 ...
A pitfall in tcl is the internal string encoding, its based on utf-8 format.
Most mp3 players can't handle utf-8 so its up to the user of the tcl-id3lib
module to do conversion from utf-8 to the desired encoding. Unicode is supported
by most players. But ISO-8859-1 and other local charsets are supported by all.
Tcl has various ways to handle with encoding itself so make use of them.