Merge branch 'release/2.9.0' into develop
Add Drag&Drop of groups
Fix typo in JS code
v2.9.1 Hotfix release

* hotfix/2.9.1:
  Fix typo in JS code
Merge branch 'hotfix/2.9.1' into develop

* hotfix/2.9.1:
  Fix typo in JS code
Add copy of channels in overview
Make login as modal dialog
Adjust configuration handling
Adjust models
Add real ORM with generated base classes
Major frontend updates
Add API r4
Update SQL
Change Setup logic
Minor fixes
Adjust tariff view
Add legend to index view
Fix History model
Remove Model logic
Fix endless loop in public view