used @openbsd.org initially by mistake and got copied around in most files. Since this has nothing to do officially with the OpenBSD project, use my own email address.

the consume mode implicitly drops the tracks from the playlist when played 'till the end (note that skipping over a track doesn't trigger the consume mode - yet?)

see GitHub issue #1

originally i tried to match the previous or next song in the playing queue after a load command if the current song was not matched. The idea is ok-ish, but the implementation was broken and become a no-op after some recent refactoring in that area.

`amused show -p' generates a listing in the form of song > current song song ... This adds an heuristic to `amused load' so that the current song can be set if it's prefixed by "> ". It's particularly useful when re-importing the state from a previous run.

IMSG_ERR needs a playlist_dropcurrent(), but otherwise is just the same as IMSG_EOF: the current song ended and we need to move forward. To unify, set current_song to NULL in playlist_dropcurrent, which make sense since right after it we're not playing anything.

this avoids the player skipping two songs on failure.

playlist.songs[play_off] is not a good representation for the current playing song after all. After a `load' command, or a flush request, the play_off changes but we're still playing the "old" song. This saves the current song in a dedicated variable that's updated upon playlist_advance and playlist_previous, thus givin a more accurate view.