This reduces size of this file from currently 60 to 16 KB.

This allows the OS to sort the files into the right categories
(movie, audio, ...).

close #9778

refs #3178

Fixes #10318

ref #10318

For some reasons, the video part does not work yet.

(It is already tested in dist(check) but that is way too slow.)

This reverts commit 2363d00e.

Twolame converts from FL32 to S16 internally anyway so no point
using this instead of converting inside vlc.

Pointed-out-by: Rémi Denis-Courmont

Specifically, the crash at the end of playback was happening when end trim was
not being subtracted from i_buffer.

as FL32 is used in filters/resamplers also, this hopefully
removes a need of one conversion.

This avoids checking that the playlist exists over and over again. The
playlist always exists when an interface is running.

Also remove a useless and unsynchronized test.

This restores symmetry in the playlist API, but most importantly, it
is necessary to fix some corner case races (in later commits).