Improve discussions

* check for outdated discussions by comparing diff
* improve discussion UI

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Cleanup

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'improve-discussions' into 'master'

Improve discussions

Implement outdated discussion detection