chore: Updated installation instruction for Sourcehut

Refactor: Modified highlight for operators and numbers

Refactor: Heavy performance improvements

Refactor: Simplified SimpleArgument, captures more cases

Refactor: Highlighted vars to strings, changed fields to match

Refactor: Switched list head and arguments types

It looks more natural with these colours.

Feat: Made my own colorscheme based on the original

Merge pull request #1 from adarshp/patch-1

Adding durative-action

Adding durative-action

Added plugin files

Update README.md

Initial commit