Status:
 (1) Working flags: 'Unsynchronisation', 'Data length indicator'
 (2) Reads pretty much all standard TAGs
 (3) usage is compatible with id3v2 linux utility, see usage()
 (4) Writes only selected TAGs, as per "usage"
 (5) Issues:(a) Other flags need to be implemented
            (b) While writing a TAG into output file, skips writing all similar TAGs
                (Error, It should skip TAG with same 'Content type' only)