Minimal audio player based on libav

To deploy it in sculpt add the following snippet to the deploy config
(or better yet, put it into a launcher file) and adapt it to your
system:

  <start name="audio_player" pkg="xxxx/pkg/audio_player/yyyy-yy-yy">
    <config state="playing">
      <report progress="yes" interval="1" playlist="1"/>
      <vfs> <fs label="media"/> </vfs>
      <libc/>
    </config>
    <route>
      <service name="Audio_out"> <child name="audio_mixer"/> </service>
      <service name="File_system" label="media"> <child name="media_fs"/> </service>
      <service name="Report"> <parent/> </service>
      <service name="ROM" label="playlist"> <child name="media_rom"/> </service>
    </route>
  </start>


The playlist ROM contains a list of audio files that should be played. Its
format is as follows:

  <playlist mode="repeat">
    <track path="foo.ogg"/>
    <track path="foo.flac"/>
  </playlist>