Fixes #1508.
Annotate $app type in front controller
restoring popover initialization.
Video Modal Fix.
Merge pull request #1553 from xiaohutai/bugfix-1508

Fixes #1508.
Merge pull request #1555 from adrianguenter/develop

Annotate $app type in front controller
Merge pull request #1559 from xiaohutai/bugfix-for-videomodal

Fix Modal for Video Fields.
Fix for buttons of Select and Taxonomy/Category fields.
Refactoring of page template handling
- Easier to select the kind of page (nav, no nav, popup)
- All menu entries are now easier to mark active (page_type block replaced by page_nav)
- Unified no-nav-page template
- Messages display block width now depends on where it is used
- Error page now styled
Merge pull request #1560 from xiaohutai/bugfix-for-selectbuttons

Fix for buttons of Select and Taxonomy/Category fields.
Merge pull request #1561 from rarila/page-extends

Refactoring of page template handling