Grammar overhaul

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This pull does numerous things:

• Fixes an error reported in github/linguist#3924
• Makes token naming consistent with Textmate, Sublime and Microsoft conventions
• Permits line continuation in class and function definitions
• Add support for single line blocks
• Adds feature ideas from sublimehq/Packages#2650 (anonymous functions, operators, punctuation, newer number formats)
• Highlights assignments with a meta scope that can be filtered out in injection grammars
• Use correct token name for section comments
• Highlight cell indexes and function calls appropriately (matrices are highlighted as functions!)
• Vast improvement to property validation highlighting
• Adds import highlighting for fun!

Closes #26. Closes #27. Closes #35. Closes #36.

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Tests aren't running because vscode-grammar can't backtrack in the new single line block tests. Will fix tomorrow.

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Fixed tests.

@rlivings39 @gauravsavadi You're probably busy with R2021b but what's the ETA on merging this pull

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All done now :shipit: 🚀

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I have signed the CLA (I'm Munin!) however I haven't completed the work yet. Trying to figure out global readwrite variable matching atm

Noting here that I've done readwrite operation matching via injection grammar in the vscode-matlab repo

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@gauravsavadi requesting review on this PR