Add an option toggle for whole word search

[trbielec]

Summary

Great extension, I use it all the time, and mapped the Caps Lock key in Chrome to it using Karabiner+BTT. So useful! One thing that bothers me a bit:

100% of my searches are for whole words (exact strings). The current search is looking for any of the search characters, which brings up too many irrelevant results and the bold text formatting makes them harder to read.

If I search "Github" I'd like only tabs with "github" in the name or URL as an exact match. Currently it shows results like "Twitter" because they share a couple characters.

I'd like to change the default search, but in case this is a common use case an option may be a safer solution.