Changed api for main menu entries.
Enhanced http error pages using a classed based views.
Moved dashboard and select widgets view from projector to core app.
Also some small clean ups.
- Always use templatetag 'absolute_url' instead of (depricated) 'model_url'.
Search and replace all old arguments: edit -> update, view -> detail, delete
- Fixed bug in setting default value in 'absolute_url' templatetag
(default value is defined in models.py only).
Updated 'backend' template.
- Fixed agenda widget for special slide views (e.g. list of speakers, summary).
- Fixed back to motion(s) link
- Set icon for list of speakers widget.
- Fixed overlay widget layout of form elements.
- Added submenu with other config_pages to version.html.
- Updated completly DE translations, fixed EN strings.
- Coding style: Use correct ugettext and ugettext_lazy strings. Use "as _" for ugettext only.
Updated translation.
- Improved projector template (clock image, fixed facicon, added subtitle for list of speakers)
- Changed permission strings ('oneself'). Added check if group(pk=3) exists.
- Added event name and description to base template. Some minor template layout fixes.
- Use static subtile (no context var). Show last 2 old_speakers for projector.
- Cut old_speakers.
- Projektor template style changes (e.g. overlay list of speakers).
