The current regex for ruby constants has an error and matches way more than it
should. It overwrites the reserved words and most variable names with bright
blue - making it hard to read. Change the regex to match exactly 1 of $|@|@@
instead of matching 1 or 0.
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
