add an humanize function that prettify shortcut on macos
Add notion of actions to celltoolbar

modify toolbar.js to be able to deal with actions.

modify maintoolbar to deal with the new action architecture

add a way to triger notification widget hiding
fix john coments
Fix comments

move humanize-map out of function call to have only one instance
complete unicode mac symbol
adresses Min comments x2
fix rebase after kill of layout manager
note to self
make pseudo action in their own dcit.

make test more reliable by adding data-attributes to buttons.
saving notebook does not run cell.

Thus running cell instead of saving notebook
return elements instead of append them directly

+ jshint fixes
Merge pull request #6700 from Carreau/actions-2

Use notebook actions in toolbar