Make replies take up less space

#### Is your feature request related to a problem? Please describe.

I feel that replies take up a lot of space on the timeline. They can take less.

#### Describe the solution you'd like.

Here's a mockup of what I'd like:


1. When you reply to a post that is not directly above yours, a single line of text is shown inside a grey chip. When clicked, it takes you to the original message.

2. When you reply to a post that is directly above yours, not even that grey chip is necessary. A green line connecting your message to the original one is shown instead.

That way, little extra space is used even if there are lots of replies on the TL.