Tweak hint scoring for filtered hints.
Tweak hint scoring for filtered hints.

This tweaks the scoring of hints for filtered hints.

Specifically, it scores matches at the start of the text or the start of
a word higher than whole-word matches.

This is intended avoid the phenomenon whereby adding matching characters
to the filter causes the selected hint to change.

gdh1995/vimium,poacher2k/vimium,gdh1995/vimium,philc/vimium,poacher2k/vimium,philc/vimium,poacher2k/vimium,smblott-github/vimium,decaffeinate-examples/vimium,decaffeinate-examples/vimium,gdh1995/vimium,decaffeinate-examples/vimium,philc/vimium,smblott-github/vimium,smblott-github/vimium