#5 Helixplayer support

[Tobias Burnus]

While it is nice that mplayer is supported, it would be
great if
Helixplayer/Realplayer could be supported as well.

Helixplayer is GNU and both are rather wide spread and
have a good comunity support.

Adding/maintaining the codec should be not too difficult.

See https://player.helixcommunity.org/
and https://bugs.helixcommunity.org/show_bug.cgi?id=2850