Add settings for vertical/horizontal tabs

[stu-beacon]

I like vertical tabs but it's a bit redundant having both vertical and horizontal at the same time. Please add display settings that allow turning on/off vertical/horizontal tabs.

[DanPristupov]

The first button on the toolbar

[stu-beacon]

@DanPristupov that just toggles the vertical tabs on/off. But the horizontal tabs always remain, even when vertical tabs are enabled. It's redundant to have both on at the same time.

[DanPristupov]

Horizontal tabs are added by macOS. They can't be disabled. It works the same, for example, with vertical tabs in Safari.