Rewrite syntax definition

[FichteFoll]

The ASS syntax defiition always annoyed me because of its wrong scope usage (notably entity.name for style references), so I finally decided to tackle those. And while I was at it I realized I could do a much better job at highlighting, so I implemented a couple new features and more finegrained highlighting comparable to how ASS is actually parsed (by VSFilter).

• Tags in parentheses are recognized and highlighted, notably \t and \iclip.
• All known supported tags are recognized (via http://docs.aegisub.org/3.2/ASS_Tags/)
• Tags are recognized even when they only start with a recognized tag name (yeah, it's stupid).
• Scope names are normalized across the board. No upper case characters and adhere to current conventions, except for constant.numeric.* where I just picked whatever seemed potentially useful.
• Highlight lines for Aegisub's karaoke templater which is used in many places, with inline Lua highlighting for code and template lines
• Remove YAML quotation where useful, especially for multi-line expressions.
• Only scope the text part of comments as comment. Less disruptive for flow and the other fields still matter when you decomment them.
• Vector drawings are highlighted whenever a \p1 tag occurs anywhere in the override block, not only if it's the only tag.
• Dynamically switch between override tags and comment in a block.
• Override tags get a source.ass.tags scope because they are not text.
• Probably more?

Here are a few screenshots from an example script:

(Ignore the linter errors that I got for free thanks to SublimeLinter.)

See also the extended test file.

I left the commits as I made them because I imagine you'd squash them anyway.

[jfcherng]

A big thanks for this. :+1: I probably would never rewrite it by myself since its "looking" is kind of good enough for me.

Would you mind providing a decent miscellaneous/demo.ass for the purpose of a quick visual view. The current one is just too simple. :laughing:

[jfcherng]

Thank you @FichteFoll :heart: