* Placeholder cell to add new real cells
* Fix links in notebooks to show correct color, rely on angular ngif for placeholder
* Fix failing test where one cell was expected by default
* Remove unnecessary TODO
* Allow for cell unselection
* PR Feedback: use event.stopPropagation() when multiple events can fire
* Ensure markdown goes into Preview mode when cell not selected
* Hide ToggleMoreAction for inactive cell
* Revert wrong merge
* Undo bad merge
* Enable markdown to hide ToggleMoreAction
* Resolve PR comments
* Fixed the name
* Change name
* Fix toggleMoreActions by passing in CellContext instead of just nb model
* Fixed the warning by removing notificationService from the caller
* Added toggle more actions to cell
* Resolve PR comments
-- Added INotificationService for notification msg
* Reduced ToggleMoreAction to smaller size. So the dropdown could be displayed closer to it instead of at the buttom of the cell.
* Initial toolbar work
- This is in-progress and needs additional fixes
* Resolve PR comments
* Added empty kernel and hook up with Kernel dropdown
* Resolve PR comments
* initial work for addig code and code cell type
* add cell model and create editor for each cell
* formatting
* fix resizing issue
* small changes
* address comment
