Regexes should have higher priority on code

[luizperes]

Regexes should have priority over strings, ids, numbers and operators because it will define custom rules to the parser.

At the moment, it has one of the lowest parser priorities. https://github.com/github-aux/linguist-unknown/blob/chrome/src/scripts/ling-highlighter.js#L298

[luizperes]

Regexes will have lowest priority in the code, once that would cost a lot of speed for the parser because of the match, therefore we won't implement it.