vscode extension

Hi!

This is more an enhancement, but thought it would be cool to have an extension in vscode for this spellchecker.

I have tried others and they don't seem to extend well beyond US english.

With the ability to have it be interactive it can add to the `.spelling` file or in vcsode add it with the Problems.

Not sure how hard or how to do it, but hopefully someone might want to endeavour!