Rewrite hover effect on conversations with multiple participants in css

[lislis]

We noticed that the sliding effect on conversations with a lot of participants has kind of poor performance. I rewrote the effect in css which looks way smoother and isn't that annoying once you have a lot on these conversations.
I had to cherry pick the commit from another fork and adjust it to a backbone refactor. Sry for the weird git things, it made me go crazy.
Opinions and suggestions welcome :D

[jhass]

Looks nice! If you could just indeed clean up the git history a bit? git checkout rewrite-conversation-hover-in-css; git rebase -i e2a5912;, there choosing squash for your last two commits and then just git push -f origin rewrite-conversation-hover-in-css.

[svbergerem]

Great! :) Unfortunately conversations with more than 2 participants now have a bigger bottom-margin. It would be great if you could fix that.

The participants div has some additional padding-top and margin-top. Only adding that for hovered conversations and setting it to 0 for all others should fix that. Maybe you could also add a transition for those two properties.

[lislis]

@svbergerem ha you're right :) I just assumed everything uses border-box. I pushed the fix

[svbergerem]

Awesome, the hover effect feels much more mature with this PR. Thank you! :)

[lislis]

Yaay!

[goobertron]

Thanks a lot, @lislis!

[Flaburgan]

Thank you!