Update language server, ensure backward/forward compatibility

[PeyTy]

• Option to use constant TCP connection instead of REST (btw use this mode by default?)
• Handle in-compiler crash gracefully (this is done, refactor and commit)
• Sidebar outline improvements, take types from Typer when possible?
• Go to definition (Ctrl+Click) / Go to type definition
• Ensure backward/forward compatibility
  • FP-style table of callbacks for kinds of lint reports (for things like hints, in future)
• Highlight words, operators and blocks properly
• More info on hover (var type & mutability, optimization opportunities, etc)
• Refactoring features (like rename class/etc, warn about name clashes (global and within one file cause aliases))
• Fix underline positions (use spans)
• Find all refs
• Dim unused
• Other common LSP features to this list
• Update snippets
• Shallow type check (i.e. don't stop after some type errors)
• Better cache
• Dim unreachable code
• Stop type check when desired lint info is reached (optimization)
• Autorun Hexa server
• Inline dimmed inferred types
  • for i TYPE in e
  • var v TYPE let v TYPE
  • Option to disable this
• Lint of unsaved file
  • Project-related
  • Independent
• Autocomplete improvements
  • Local vars/funcs in current block
  • : Type
  • Fields .HERE
  • Option to insert colons for arg names func(name:, name:) also always show them in autocomplete list