Setting this flag will tag any matching tracks with kRoleMain.
The player will then know which tracks should be default when there
is not a language match.
Closes#155
Change-Id: I827304c49e345d07b1e76f7a46421b60f228f0ba
For mp4 outputs, a metadata box with version information is added to
moov box.
For mpd outputs, a text comment with version information is added in
the beginning of mpd file.
Issue #60
Change-Id: I783ba370781c0a8f77c910ff1172bad2e7edff75