Build TextMate grammar from YAML

[Marcelotsvaz]

I want to implement #32 and fix some bugs in the syntax highlighting but working with the TextMate grammar in JSON is a miserable experience. Building the JSON from a YAML file is a huge improvement.

YAML Advantages Over JSON

• Multi-line strings for commented regexes
• No double escaping regexes
• Basic code re-use with YAML anchors
• Less typing with unquoted strings
• No complains about trailing commas (this drives me crazy in JSON)

Later we can add variable substitution and includes if needed.

What I Did

• Converted the JSON grammar to YAML
• Did some manual cleanup (I will do more later)
• Created a build script to convert it back to JSON
• Added some instructions in CONTRIBUTING.md

Building the Grammar

yarn build:grammar

This will run build/grammar.mjs.