Highlighting lexer

[ice1000]

For every time user edit a file, the LSP unload it. We can do better:

• We lex the file on save.
• We provide precise token-based highlight for the file, on save, based on the lex result.
• We provide navigation on Ctrl+L Ctrl+L (already done).

This is inspired from @agda.

@imkiva wdty

[imkiva]

I remember agda-vscode maintains an edit-list to correct highlight positions when the user edits the file. But VSCode seems not to fire certain events as user types (instead, it fires a file change event on save).

[imkiva]

Oh I have a solution! Your suggestion is pretty awesome!!!!

[ice1000]

What solution?

[imkiva]

On save, the server sends the highlight result from SyntaxHighlight to client. The old approach (sending highlight result after C-l C-l) is deprecated.