can't seek after exiting zoom with mouse back button

[sshane]

from #486. back button in the UI works though

cant.seek.properly.with.mouse.back.mp4

[0x7B5]

This is getting caused because state.loop doesn't get updated properly when using mouse back button. Looking into it rn.

[sshane]

The history middleware used to reset it to the route zoom range, but now it doesn't execute

[0x7B5]

That PR should fix it. As a side note, combining zoom and loop is probably not a bad idea (#461).