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Closes #4 and #5

See merge request swtp-2019/arsnova-lite!15

Mark as correct

Closes #8

See merge request swtp-2019/arsnova-lite!14

Comment component

See merge request swtp-2019/arsnova-lite!13

Improve comment creation

See merge request swtp-2019/arsnova-lite!10

Comments list view

See merge request swtp-2019/arsnova-lite!9

Merge fix for feedback

fix path for feedback view

See merge request arsnova/arsnova-lite!164

use shortId for frontend url
use roomId for subscribing to backend channels

Diagrams for planned comment feature

See merge request swtp-2019/arsnova-lite!8