Add support for deleted annotations

[damien-king]

Hi!

Thanks for making this, it's super helpful :). I would create a PR but no permissions.

Hoping to add:

zannotationdeleted to const ANNOTATIONS_QUERY in constants.js

and something to the effect of

    var annotation = {
      ...,
      deleted: rawAnnData.ZANNOTATIONDELETED === 1 ? true: false
    };

So I can filter out deleted annotations when I'm querying.

Thanks!

[solean]

Hey. I think you should be able to submit a PR if you fork the repo and create a new branch. If not, I can make the change but you should get the commit credit since it was your idea lol.

[solean]

Added in commit: d63131