Sort movies and tv shows collections by 'sorttitle' attribute

[PunyIron]

Sort movies and tv shows collections by 'sorttitle' attribute instead of 'title' attribute in default. I think this is the real reason of exists of 'sorttitle' attribute.

In some languages, sometimes is needed to use 'sorttitle' because 'title' contain accents, which are not good for correct items ordering.

Thanks for considering.

[yuuzhan]

Pretty sure this file is all that needs editing: https://github.com/xbmc/chorus2/blob/60e543306195cd2b46dc77b36688e321ec1fba0f/src/js/apps/filter/filter_app.js.coffee#L18

      {
        alias: 'sort title'
        type: 'string'
        defaultSort: true
        defaultOrder: 'asc'
        key: 'sorttitle'
      }

Not sure how to build / test it :P