Bookmark traversal fixes. Changes:   - use natural order for bookmark traversal   - eliminate use of O(N^2) `shift`
Bookmark traversal fixes.
Changes:
  - use natural order for bookmark traversal
  - eliminate use of O(N^2) `shift`

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