* improve fenced code recognition for markdown lexer

* improve inline code detection

* improve detection of some Markdown keywords

* remove Markdown recognition of code indented by 4 spaces as reliable detection is not possible with regex

* crystal: drop all classes from builtins; these aren't normally highlighted

("normally" meaning all other highlighter tools)

* crystal: fix percent-strings, drop Ruby-specific arbitrary delimiters

It seems that Ruby supports strings such as `%*text*` where `*` can be anything. But Crystal never had anything like that. It does, however, keep `%|text|`, so add a case for that.

* crystal: update keywords and builtins

* crystal: fix string literals and escape sequences

Update list of escapes. Support Unicode escape sequences.

Also remove the Ruby-specific `:@foo` symbol syntax, Crystal doesn't have it.

* crystal: uppercase identifiers aren't always constants

Make `FOO::Bar` be highlighted like `Foo::Bar` would be, rather than like `FOO`

* crystal: annotations can be namespaced

Highlight the entire inside part of `@[Foo::Bar]`, not just the `Foo` part

(these used to be named 'attributes' but the official name is 'annotations' now, so I also change that)

* fixup! crystal: fix percent-strings, drop Ruby-specific arbitrary delimiters

* Unicode support for Coq

Catch-all lexing for `Name.Builtin.Pseudo`, as in the lean lexer.

This fixes #678.

* Coq lexer: improve `analyse_text`

* Add a test for Coq

Co-authored-by: Mestery <48163546+Mesteery@users.noreply.github.com>