Browser editor with preview

There are two versions of this editor:

editor.html is a toy/demo with no backing database.
That editor can be viewed directly locally with:
```
git clone https://github.com/ourbigbook/ourbigbook
cd ourbigbook
npm install
npm run build-assets
chrome editor.html
```
It also appears at docs.ourbigbook.com/editor hosted simply under GitHub pages.
a similar looking editor will also appear on the OurBigBook Web, but this time linked to the database.
That more advanced editor will actually save results back to the database, and show allow preview of features such as linking to headers of other pages.

Issues for the editor are being tracked under: github.com/ourbigbook/ourbigbook/labels/editor

We must achieve an editor setup with synchronized live side-by-side preview.

Likely, we will first do a non WYSIWYG editor with side by side preview with scroll sync.

Then, if the project picks up steam, we can start considering a full WYSIWYG.

It would be amazing to have a WebKit interface that works both on browser for the and locally.

Possibilities we could reuse:

 Ancestors