Should address issu #19

perfect. merged!

Awesome! Thank you.

playlist: "p" in the current playlist should just play the song

See merge request mpdel/mpdel!46

By default "p" adds the song after the current song in the playlist
and starts playing it. In the current playlist, we don't want "p" to
add the song to the current playlist because it's already there.

Navigel method

See merge request mpdel/mpdel!45

ffUpdate navigel dependency

See merge request mpdel/mpdel!44

This avoids a bug with buffers having the wrong major mode.

The code is now much simpler. Hopefully, all features are still there
but time will tell. At least, the code is now much simpler.

This variable was never meant to be private.

When adding single tracks to a playlist from a nav buffer, move the
point to the next line afterwards. This provides some feedback to the
user that the interaction was successful as well as allowing adding of
multiple tracks in rapid succession by repeatedly pressing `a`. It
also prevents accidental duplicate adds. This behavior is in line with
that of e.g. the `dired-mark` command in dired buffers.

When adding multiple tracks via a region to a playlist, deactivate the
mark afterwards to provide some feedback to the user in this case,
too, as well as preventing accidental duplicate adds. This too is in
line with the behavior of modes like dired.

Without this patch there is wonky behavior when deleting multiple
tracks via a region with `transient-mark-mode` from a playlist. If the
last track was included in the region, the whole buffer would end up
getting marked. Otherwise, the end mark would be removed but the start
mark would be left in place.

This file is part of libmpdel, not mpdel.