Filter hints mode should automatically use numbers for hints
Filter hints mode should automatically use numbers for hints

Also tidy up backspace handling.

douglas-larocca/vimium,csmalin/vimium,smblott-github/vimium-smblott,willsALMANJ/vimium,cyrixhero/vimium,smblott-github/vimium,Robinson10240/vimium,tuchangwei/vimium,PrestanceDesign/vimium,jb55/vimium-plus,borgified/vimium,philc/vimium,PickRelated/vimium,crazypenguincode/vimium,mrmr1993/vimium,wildeyes/vimium,mrmr1993/vimium,elderbas/vimium,smblott-github/vimium-smblott,zhangmin510/vimium,borgified/vimium,philc/vimium,PickRelated/vimium,Robinson10240/vimium,VPashkov/vimium,decaffeinate-examples/vimium,shaung/vimium,bkudria/vimium,jb55/vimium-plus,decaffeinate-examples/vimium,smblott-github/vimium,bkudria/vimium,poacher2k/vimium,tuchangwei/vimium,cyrixhero/vimium,csmalin/vimium,PrestanceDesign/vimium,dimatter/vimium,willsALMANJ/vimium,justalittlenoob/vimium,Lw-Cui/vimium,justalittlenoob/vimium,llimllib/vimium,elegantwww/vimium,VPashkov/vimium,PickRelated/vimium,Robinson10240/vimium,smblott-github/vimium,gdh1995/vimium,crazypenguincode/vimium,douglas-larocca/vimium,hhsue/vimium,hhsue/vimium,Lw-Cui/vimium,zhangmin510/vimium,dimatter/vimium,Lw-Cui/vimium,elderbas/vimium,dimatter/vimium,justalittlenoob/vimium,elderbas/vimium,bkudria/vimium,wildeyes/vimium,tuchangwei/vimium,philc/vimium,willsALMANJ/vimium,PrestanceDesign/vimium,cyrixhero/vimium,decaffeinate-examples/vimium,hhsue/vimium,Aleroniponi/vimium,borgified/vimium,gdh1995/vimium,elegantwww/vimium,poacher2k/vimium,Aleroniponi/vimium,VPashkov/vimium,mrmr1993/vimium,gdh1995/vimium,csmalin/vimium,douglas-larocca/vimium,wildeyes/vimium,poacher2k/vimium,zhangmin510/vimium,Aleroniponi/vimium,elegantwww/vimium