From now on, struct Song will be used by the database only, and
DetachedSong will be used by everybody else.  DetachedSong is easier
to use, but Song has lower overhead.

Prepare to migrate away from GLib.  Currently, we're still using GLib
as a backend.

Make sure the player "owns" the next_song object, so nobody else can
free it.

For simpler seeking within current song.

Use a shortcut in playlist_seek_song(), don't call
playlist_play_order() because that would reset the "paused" state.

Allocate a player_control object where needed, and pass it around.
Each "client" object is associated with a "player_control" instance.

This prepares multi-player support.

After we've been hit by Large File Support problems several times in
the past week (which only occur on 32 bit platforms, which I don't
have), this is yet another attempt to fix the issue.

No more CD player emulation.  The current behaviour of "previous" is
difficult for a client to predict, because it does not definitely know
the current position within the song.  If a client wants to restart
the current song, it can always send "playid".

Renamed all playlist functions to non-CamelCase.

Commit f78cddb4 introduced a regression: when the playlist reached its
end, MPD did not reset the "current song" pointer anymore after stop.
Add a "current = -1" code line.

Renamed playerSeek() to pc_seek() to get rid of CamelCase.  Convert
the return value to bool.

To determine whether to rewind the current song or to go to the
previous song, use a GTimer instead of manually diffing time(NULL).

Consume mode removes each song played

When single mode is enabled, after current song it stops playback,
or it replay same song if repeat mode is activated.

The smartstop feature is a way to tell mpd to stop playing after
current song.
This patche provides:
- 'state' command returns 'smartstop' state (1 or 0)
- 'smartstop' can activate or not the smartstop state
- when song is terminated, mpd stops playing and smartstop is set to 0

This updates the copyright header to all be the same, which is
pretty much an update of where to mail request for a copy of the GPL
and the years of the MPD project. This also puts all committers under
'The Music Player Project' umbrella. These entries should go
individually in the AUTHORS file, for consistancy.

The queue update after a seek was wrong: the queued song is cleared by
a successful seek.  This caused queue/cross-fading problems after a
seek.

If a new song is queued before calling playerSeek(), then the player
and the playlist enter an inconsistent state, because the player
discards the playlist's "queued" song in favor of the seeked song.

Call playlist_update_queued_song() after playerSeek().