Screen-based gap size

[morrolinux]

Thank you for this very useful extension!
Would it be possible to make it so one can decide what gap settings to use based on the screen name?
I've got a secondary screen in portrait mode and left/right gaps make it unusable on the already tight horizontal space.

Even just a "disable for this screen" option would be very nice!

[mipmip]

Would be possible. I think starting with disable for secondary screens would be a start. PR's are welcome :)

[morrolinux]

I've implemented the "disable selected monitor" feature in #29
I initially thought "disable for secondary screens" was the best way to do it, but then I thought of multi-monitor setups, and I think it makes more sense to be able to exclude the only vertical monitor rather than all monitors except the main one.