Bug Fixes:
* Fix icons in room view for both roles

Features:
* Adds a counter for the comments
* Adds a badge in the comment view that counts comments / filtered comments
* Adds a guest login for speaker role

Performance improvements:
* Enables Angular Ahead-of-Time compiler
* Improves loading strategy for Service Workers

General improvements:
* Optimizes dark theme for better readability
* Only shows the toolbar for the comments when there are more than 3 comments
* Pins the searchbar for the comments to the top
* Adds ID and local time to the header component in the comment view
* Improves overall wording

Bug Fixes:
* Closes presentation view for comments on pressing ESC when in browser fullscreen
* Fixed not being able to scoll in room settings

Add extraction command

Generated angular project 'arsnova-angular-frontend' by angular cli.