Make tab tooltips optional

[cockroach]

The current tooltips can be a bit irritating in some cases, eg. when using a tiling window manager which changes its layout when a tooltip appears. This branch fixes that for me by making the tooltips optional.

[blitzmann]

Interesting. I will take a look at this later next week when i get back holiday. What exactly happens with your window manager (also, which one is it)? Mind providing a screenshot?

EDIT: I can merge this if needed, but I would like to address it so that it doesn't cause issues in such cases. Gonna need a bit more info ;)

[DarkFenX]

They are also rather annoying for me (huge, rather sluggish and cause additional system-level popups on gnome3, because they are implemented as app windows which appear out of focus). If many people dislike them - might even consider disabling them as default.

[blitzmann]

I didn't know they caused such issues on Linux. I've never really used them, nor do I really like them or see the value in them. I wonder how many folks actually use the information it contains... I will merge but keep it opt-out for now.