Presentation mode

1. Preparation:

• Revise content presentation and statistics components for the use in presentation mode
• Revise survey component for use in presentation mode
• Refactor bar components and revise for use in presentation control bar
• Revice qr code component for use in presentation mode
• Revise answer count component for use in presentation mode
• Extend notification service for use in presentation mode
• Revise comment components for use in presentation mode

2. Realization:

• Modify app for displaying presentation mode
• Create a presentation module and make components accessible under /presentation/<shortId>
• Create a control bar for controlling navigation and active features
• Allow controlling presentation mode with keyboard
• Create components for showing main features

3. Final touch:

• Scale content statistic and survey views for presentation and fix some styling issues
• Remember current content index when routing between features
• Show current content index and how many contents are in group
• Allow to lock/unlock contents
• Allow to zoom comment presentation with keys
• Allow to sort comment in presentation
• Hide bar and mouse after seperate timeouts
• Refactor control bar template and styling
• Do some minor improvements

Closes #728 (closed)