Bug 5175: Add missing Title + Subtitle to 3 styles

- Britle:
    Supplement propgroups and CSS to display and customize Title,
    Subtitle, Pagetitle.
- Negatives:
    Supplement Page::print to add call to print_global_title() and
    print_global_subtitle().
    Supplement propgroups and CSS to display and customize Title
    and Subtitle.
- Skittlish Dreams:
    Supplement Page::print to add call to print_global_subtitle().
    Supplement propgroups and CSS to display and customize Title
    and Subtitle.
Merge pull request #537 from meludame/bug5175/AddMissingSubtitles

Bug 5175: Add missing Title + Subtitle to 3 styles