The list was taken from https://www.nano-editor.org/dist/latest/nanorc.5.html.
Previously the list of keywords were split into two regexes, this didn't seem
to serve any purpose besides making the code harder to read, so I have
collapsed them together into one.
Duplicate syntax definition names may cause problems.
Since nano comes with predefined all-lowercase syntax definitions,
we use uppercase letters everywhere to reduce the risk of future conflicts
