Use TYER instead of TDRC for year on v2.3

ID3 v2.3 uses separate 4-byte TYER, TDAT, and TIME frames to
store the recording time, as opposed to v2.4's unified TDRC
frame:

  http://id3.org/id3v2.3.0#Text_information_frames_-_details
  http://eyed3.nicfit.net/compliance.html
Merge pull request #3 from derat/date

Use TYER instead of TDRC for year on v2.3