DFXP Viewer Application

For primarily historical interest, see [1] for a (now dated) TTML (aka
DFXP) viewer. I have not yet tested this against the current TTML1 to
determine, e.g., if it supports the current TTML namespaces. If it does
not, then it may still be possible to run a TTML1 file on this by modifying
it to use the older DFXP namespaces, about which see [2], the CR of DFXP
that preceded this viewer release.

[1] http://lists.w3.org/Archives/Public/www-archive/2014Sep/0002.html
[2] http://www.w3.org/TR/2006/CR-ttaf1-dfxp-20061116/#vocabulary-namespaces