refactor the guts of `$tag->print_frames` into `$tag->get_frame_for_display`
refactor the guts of `$tag->print_frames` into `$tag->get_frame_for_display`

this allows other scripts (e.g. `mp3diff` to display frame values similarly, but using their own formatting
also now better handling the case where the value is larger than the expected width by adding an ellipsis character
also now allowing the default width to be overridden

barefootcoder/music,barefootcoder/music,barefootcoder/music