Fixes#4217 Adds notifications
- Created a class to define notification-objects, which should notify other persons editing the same motion.
- Added functions to send notifications, listen to them and unsubscribing them.
- Added a warning-function to the `base-view.ts`, which raises the snack bar with the given message and has no duration.
Fixes#4217
- Removed unnecessary lines of code.
- Fixed merge.
Prettified
- Added a random number to identify different user.
- Now the user can sign in as the same user, but still receive a message if multiple people edit the same motion.
Fix the detail of motions
- If the user does not click to edit, then the `editNotificationSubscription` was not set.
Add view for full history and History Repom TimeTravelService
Add function time travel routine
Updated the HTTP Service, fixed usage of storage, OSStatus Service, fixed loading of the history data
