Only show username in chat history when author of message block changes

Example screenshot visualizing the problem:

On the other side, this is how Fractal does it:

Note the two messages at the top. Two messages share the same author, therefore the author name is omitted the second time.

changed milestone to %GTK Next

added T: feature label

User feedback:

Instead of putting "Myself" above messages, we could also change the background color of own messages a little bit to visually distinguish messages. Similar to the hover color when being on top of messages.

mentioned in commit bd2debb3

mentioned in merge request !58 (merged)

changed milestone to %GTK 0.1.0-beta1

assigned to @nicoalt

mentioned in commit daeae191

mentioned in merge request !59 (merged)

closed via merge request !59 (merged)