todo.md

Update README

Add implementing section

• Client must implement a handler for the "mcfunction/shutdown" notification, to stop the server gracefully from the server side.
  This notification should make the client send the server a shutdown and exit request.

Custom protocol commands

• mcfunction/shutdown (c <- s) (required): Client should call shutdown and exit. The single string argument is the error message to be shown.

Highlighting

Work out how the API for highlighting should look.

This has been postponed until microsoft/language-server-protocol#18 is resolved