Add an "exactly this word" option in the filters

[NekoJonez]

In the locales I work on, sometimes translators copy nl_NL translations over to nl_BE. We have a couple of differences, like nl_NL uses "site" and we use "website".

Now, when I'm searching in projects if everything is translated correctly... it's quite annoying to go through it all and see the places where "website" AND "site" are used. In those cases, I would find it handy if I could check an option where it searches only for the search term and other spellings don't appear.