Feature branches review please

[Ergus]

Hi:

The icomplete-vertical feature branch is pretty much ready, please if
any maintainer could give it a last review and tell me anything else
needed to merge into master?

OTOH the highlight-completions branch is almost ready too. I have more
doubts about this and maybe I will be doing some unneeded things there,
so maybe a review with some critics and advises will be very very
welcome.

Best,
Ergus