Descending messages about twake

[RomaricMourgues]

We finally decided to do a quick improve, not the final version will be implemented but something that make Messages Thread working at least a little.

• We'll implement a Messenger-like or Mattermost-like system where a notifications of the answered messages will be always visible on the end of the channel. Clicking on it will redirect / open side view to the corresponding thread.

To rediscuss with Benoit:

• May be make messages creation from bottom bar harder to force users to preferably use the "respond" button

[RomaricMourgues]

We decided to do this issue only if we have time for the remaining time in Q3.

[RomaricMourgues]

We know this issue is important. So there is an update:
we started working on the issue yesterday and expect to end it in no more than two weeks.
It will fixes several other issues (pagination, threads, scroll etc)