Search completion; retain previous (matching) suggestions.
Search completion; retain previous (matching) suggestions.

This address "UX Issue 2" from #1651.

If the user types "w lake vict" and sees a suggestion "lake victoria
perch", and continues "w lake vict pe", then we retain the previous
suggestion (which still matches) despite the fact that the completion no
longer delivers it.

This creates a more consistent, Vimium-like vomnibar UX.

Robinson10240/vimium,douglas-larocca/vimium,philc/vimium,borgified/vimium,hhsue/vimium,bkudria/vimium,elderbas/vimium,mrmr1993/vimium,Lw-Cui/vimium,gdh1995/vimium,willsALMANJ/vimium,borgified/vimium,decaffeinate-examples/vimium,PickRelated/vimium,tuchangwei/vimium,tuchangwei/vimium,PrestanceDesign/vimium,hhsue/vimium,justalittlenoob/vimium,VPashkov/vimium,Robinson10240/vimium,elegantwww/vimium,gdh1995/vimium,wildeyes/vimium,PrestanceDesign/vimium,zhangmin510/vimium,PickRelated/vimium,PrestanceDesign/vimium,Lw-Cui/vimium,justalittlenoob/vimium,Aleroniponi/vimium,VPashkov/vimium,decaffeinate-examples/vimium,csmalin/vimium,wildeyes/vimium,Aleroniponi/vimium,VPashkov/vimium,zhangmin510/vimium,decaffeinate-examples/vimium,smblott-github/vimium,bkudria/vimium,willsALMANJ/vimium,wildeyes/vimium,bkudria/vimium,mrmr1993/vimium,cyrixhero/vimium,willsALMANJ/vimium,elegantwww/vimium,douglas-larocca/vimium,PickRelated/vimium,cyrixhero/vimium,cyrixhero/vimium,tuchangwei/vimium,justalittlenoob/vimium,poacher2k/vimium,elderbas/vimium,poacher2k/vimium,philc/vimium,dimatter/vimium,smblott-github/vimium,poacher2k/vimium,elderbas/vimium,elegantwww/vimium,csmalin/vimium,Aleroniponi/vimium,smblott-github/vimium,borgified/vimium,Lw-Cui/vimium,douglas-larocca/vimium,zhangmin510/vimium,dimatter/vimium,dimatter/vimium,gdh1995/vimium,csmalin/vimium,mrmr1993/vimium,hhsue/vimium,philc/vimium,Robinson10240/vimium