New light-weight event handling:

New light-weight event handling:
1. No more needs to call snd_seq_event_free() for releasing the cell.
   But you should keep it anyway, both for compatibility and for future
   extension.
2. API is basically kept unmodified.  The sign of return values are same,
   i.e. positive integers will be returned if events exist on buffer/queue.
   But the exact value may be different from the older version.
3. snd_seq_event_input() renders the event directly from the static input
   buffer.  The function is not re-entrant.
4. snd_seq_event_input_selective() is removed.