Support for case-preserving substitution, or vim-abolish mode

[fnune]

Particularly, vim-abolish's substitution part: https://github.com/tpope/vim-abolish#substitution

With vim-abolish, instead of this:

:%s/facility/building/g
:%s/Facility/Building/g
:%s/FACILITY/BUILDING/g
:%s/facilities/buildings/g
:%s/Facilities/Buildings/g
:%s/FACILITIES/BUILDINGS/g

You can do this:

:%Subvert/facilit{y,ies}/building{,s}/g

I think if far.vim had this, it would be amazing!