movenc: add support for track names in ISML manifests

movenc: add support for track names in ISML manifests

This enables having multiple tracks of the same type which would
be treated as different things by the media server (as opposed to
different bit rate versions of the same track). According to the
smooth streaming specification, just setting the systemLanguage
tag is not enough to note that a track with the same attributes
differs from another one.

Reviewed-by: Martin
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>