[2020] Remove head bobbing

Hello,
we do not have an option to turn this off yet, but there is an issue on our bugtracker about it.

We (still) got rear-facing seats in buses and trams, i actually prefer sitting there compared to normal seats. They're pretty normal. Not having any issues.

We're going to implement a feature to disable head bobbing either in 9.0 or 9.1, though. So that's the good news.