Enables the "Format" row in "playlistinfo" responses.

https://github.com/MusicPlayerDaemon/MPD/issues/1094

New experimental code, first draft - it works, but there's a lot left
to do.  Just look at all the TODO comments.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/975

Exmaple -> Example

release v0.22.6

If the constructor moves from an ExportedSong instance which refers to
somebody else's "Tag" instance, the newly constructed instance will
instead refer to its own empty "tag_buffer" field.  This broke
SimpleDatabase::GetSong(), i.e. all songs on the queue restored from
the state file or added using the "addid" command.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1089

release v0.22.5

Needed for `requestLegacyExternalStorage` (commit ca02fb77).

The "move" command doesn't allow open-ended ranges because they don't
make a lot of sense; moving an open-ended range is only possible if
the destination index is before the range, and in that case, the
client should be well aware how many songs there are.

Closes https://github.com/MusicPlayerDaemon/MPD/pull/1057

Catch errors like that early, before invalid ranges get passed to
internal MPD subsystems.