"highlight" option typo -- hightlight

Created by: ducks

When trying to match options, Sodium is looking for "hightlight" instead of highlight.

This is occuring here: https://github.com/rjgoldsborough/sodium/blob/master/src/state/options.rs#L29

and here: https://github.com/rjgoldsborough/sodium/blob/master/src/state/options.rs#L40