Improve Chapel highlight tools

Below is a list of syntax highlighters Chapel supports or aims to support. Many live in the repository under chapel/highlight/.

Highlighters

Supported

• pygments
  • used in documentation via sphinx
• tmlanguage
  • used by GitHub via linguist
• highlight.js
  • Stack Overflow uses highlight.js but not yet the Chapel highlighter. However the above is used in the Chapel discourse.
• sublimetext
• atom
• vim
• emacs
• tex
• GNU source-highlight
• highlight
• codemirror

In Progress

• Crucible (https://github.com/chapel-lang/chapel/issues/13200)
• Google Prettify (https://github.com/chapel-lang/chapel/issues/6501)
• TextMateBundler (https://github.com/chapel-lang/chapel/issues/11842)
  • amounts to using the existing tmlanguage support noted above

Requested

Improvements

• [good first issue]: Document and/or fix any errors in our current syntax files
  • This is a great way for new contributors to get started contributing to the project, e.g. (#6899)
• Test our maintained syntax files against the compiler and/or against each other
• Find ways to minimize maintenance overhead / rely on fewer syntax highlighters
  • e.g. we could remove our tex syntax highlighting and use the minted package, which relies on pygments, for highlighting in LaTeX
• Document and employ stricter policies for syntax changes
  • e.g. If adding a new keyword, update all highlight files