* Tiny UI improvements
* Add icon for entering insert mode on a markdown cell
* Highlight selected section
* Improve contenteditable elements
* Highlight notebook/section name while editing
* Adjust result length
* Add more keyboard navigation actions
* Improve inserted/deleted cells focus and add some tests
* Some refactoring
* Run formatter
* Render evaluation outputs and result
* Fix auto-scrolling to not be interrupted by editor focus
* Add cell output tests
* Run formatter
* Show cell status
* Apply review suggestions
* Change EEx strings to Live EEx
* Set up markdown rendering, update theme.
* Improve focus and handle expanding for markdown cells
* Add keybindings for expanding/navigating cells
* Improve editor autofocus when navigating with shortcuts
* Add tests
* Render markdown on the client
* Don't render cell initial data and make a request instead
