[Bug] Auto remove _ from highlight candidate

[tmpm697]

Steps to produce:

1. chromium -> https://registry.terraform.io/providers/hashicorp/template/latest/docs/data-sources/cloudinit_config
2. select `template_file`, then right mouse click to select `Highlight Selection`
3. observe the search candidate appear in mark-my-search bar is `templatefile`

here we expect the search candidate is template_file not templatefile

[ator-dev]

Thanks, turns out I was removing too many unicode character types, including connecting punctuation 😅

I took the opportunity to improve tabbing support in the keywords bar.

[ator-dev]

Now available as 1.14.1 on Chrome Web Store.